This is not something that is easily fixed. Timing your attack correctly only comes with a combination of intuition (The creep is low, but is it low enough?) and practice (I've done this before. I know that if I hit it now, I won't kill it.) It also takes knowledge of the champion you are playing. For example, someone like Caitlyn might have an easier time last hitting because her high base damages, but someone else like Ashe might have a bit of a harder time because of her weak early game.

This problem just boils down to decision making. I have seen many people make this mistake when they see 2 low health minions at once. So they panic and auto attack one of them without any regard to which one they to hit first, then end up missing both of them. Instead, slow down and think. Identify which creep is dying faster (Hmm, this minion has 3 enemy creeps attacking it and the other one is only being focused by one.) and kill the one that is dying faster.

As a general rule, you don't want to spam your AOE abilities too much or you'll go out of mana/push the wave too quickly. Another major reason why you don't want to use your abilities too often is because you can incorrectly soften (lower the health of) a minion, which in turn leads to you missing a lot of CS. Only use your abilities to get CS if you know for a fact that you won't be able to get it otherwise. Your skill usage can be much better spent poking or trading.

If you do need to quickly push the lane, use your AOE ability after you have softened the minion wave. For example, if you're playing Ashe: Hit all of the minions a couple times so they're all very low. Then, with a single Volley you can clear all of them at once. This pushes the lane quickly and efficiently, without you needing to waste additional mana.

Learning how to last hit under turret can be very difficult if you don't know how, and sometimes even requires help from your support. The only way to get the maximum number of minions while under tower is if you waste the tower shot. This means that you let the turret focus on a minion, but you kill the minion before the tower does.

Of course, before you do this, you must soften the minion so that the tower will not kill it outright. Melee minions can take 2 tower shots and still live, whereas Caster minions can only take 1. So, if you need to get the melee minions, wait for the to shoot at it twice, and then it will be low enough for you to kill. Caster minions are a bit harder because even if the turret hits it, it won't be low enough for you to kill outright. So, you must hit the Caster minion before the tower, then let the tower attack it, and then hit it again.

One reason is to get a level advantage. When you push the lane, you are essentially making the enemy's minions die faster than yours. When the minions die, they give all nearby allies some experience. If the enemy minions are dying faster, then you get experience faster. Pushing for a fast level 2/level 6 can be extremely helpful: trading while you have an additional ability and more base health/mana than the enemy team will easily give you an advantage.

Most of the time, the side that has the level advantage will win that trade. If taken advantage of, this will give them lane dominance for nearly the entire laning phase. This is because by engaging in a trade where you have the advantage, you can force the enemy bot lane to burn important summoner spells (which won't be available for another 4-5 minutes) or even just outright kill them.

For example, in this example on the right, you can see that the Varus and the Thresh are both level 2, whereas Ezreal and Sona are only level 1. Varus immediately goes up to to attack, with Thresh very close behind him. Both parties in this situation know that Thresh has both a Death Sentence and Flay, whereas Ezreal has no escape and Sona has no heal. From the moment that Varus pushed forward for the trade, Ezreal was dead.

If you see in the next picture, look at just how low both Ezreal and Sona got. Not only that, Sona had burned Exhaust and she and Ezreal both Flashed. And all of that was simply because Varus and Thresh pushed early for the level advantage, and then they made a play using that advantage.

By forcing 2 people to have a hard time keeping up (as opposed to top/mid lane, where if you zone you only affect one person), you draw the jungler's attention away from the rest of the map. If they're constantly at bot lane, then they can't possibly be ganking other lanes (because you know, they can't be in two places at once). This frees up your own jungler to make plays elsewhere or even set up a countergank.

Now you're probably worrying about the jungler camping your lane. How do you fix this? WARD. I say it in every single one of my guides, no matter the role: VISION WINS GAMES. If you have full vision coverage, you can back off as soon as the jungler shows his face. And then after you're sure he's left, you can resume pushing and pressuring the enemy bot lane.

Now let's assume the worst case scenario: You weren't watching the map and the jungler managed to gank your lane. Between both your support and you as the ADC, you should have enough utility and damage to at least get out of the gank alive. Actually, if you're ahead enough and the enemy is far enough behind, you could potentially turn a gank into your favor.

Because CSing under the turret is inherently difficult, the enemy can lose a lot of CS. If you're constantly pushing the wave into the tower, then the enemy ADC is constantly under huge amounts of pressure to last hit perfectly. Considering this is very difficult to do, even for high ELO players, and they'll end up losing a lot of CS. If you can maintain a good CS yourself, you gain a couple hundred extra gold more than in comparison to the enemy ADC.

Coupled with the last point, you can make last hitting under tower even harder by harassing every time they go up for a ranged minion. Caster minions have a range of 600, which is more than every single ADC with the exception of Caitlyn. If you autoattack every time the enemy ADC goes for CS, then that's about 180 damage for 3 Caster minions.

In the picture, you can see how Miss Fortune just took an autoattack to the face. Vayne knew she could freely autoattack her, because the tower was focusing another target and there was a massive minion wave on her side. Even if the tower wasn't focusing another target, she could have juggled the tower aggro by attacking then quickly backing off before the tower to focused her. As a side note, notice how all of the minions are at different health. Imagine how hard it would be to last hit all of those while someone's attacking you every time you go up.

Is this realistic though? Probably not, because of attack speed limits early game in addition to the enemy actually, physically backing off. However, the point still stands that you can freely attack the enemy ADC without fear of retaliation. If they decide to attack you instead of the minion, they'll end up losing the minion to tower. Plus, your build up of minions will focus them as soon as they damage you, ensuring you win the trade.

This tactic can be used if the enemy is low on health, has no summoner spells, and your jungler is nearby. If you had previously asserted lane dominance and have been winning trades, then the enemy will most likely have much lower health than you do. In addition to that, learning to time summoner spells is a very valuable skill to have. As a general rule (not counting CDR from masteries), Flash has a 5 minute cooldown, Heal has 4 minutes, and Exhaust has a 3.5 minutes. Having this information is a key ingredient to a successful dive where no one dies.

Finally, a good idea when tower diving is to have your jungler come and help you out. Ping your jungler and let him know that the circumstances are ideal for a dive. While you're waiting on your jungler to get into position, let a massive wave of minions build up, as they'll be useful in terms of both tanking the tower and dealing damage because of the way they focus whoever is focusing you. Finally, as soon as the wave hits the tower, let your jungler/support tank the tower aggro while you dish out damage as fast as you can.

Play Video CLICK TO ENLARGE

This is one of the major reasons why you need to know exactly what summoner spells your enemy has when tower diving. If the enemy just Heals or Flashes away, then you'll be stuck tanking the tower, and your teammates will probably end up dying. If the support Exhausts you, then you won't be able to deal any damage to quickly kill the enemy.

The video above is an example of a terrible dive. If you notice, they literally followed none of the criteria that I just mentioned: Lots of minions, no summoner spells, and the jungler is in position to engage.

1. Leona engaged on the Caitlyn with no minions around her to help tank tower/deal additional damage.

2. The Caitlyn still had Flash, thus was not stunned by the Leona's Solar Flare.

3. Leona went in without Nocturne, who if you look at the minimap at the start of the video, was still far back in the first bush.

Big thanks to utopus for bringing these up! I'm just going to quote him from here:

"There are three ways of handling tower dives. The first and probably safest way to prevent a tower dive is to simply not be there. If you and/or your support are less than 33% health, and your opposing laners have full HP and summoners up it is quite possible that you will get dived. If you cannot get outside assistance, the only thing you can do sometimes is to simply farm from behind turret, and if you see your opponents making an offensive move, step back from the turret and run."

"The second way to defend tower dives is to push the minion wave, and do everything in your power to prevent the minion wave from getting to the turret. If there are no enemy minions near your turret, that means that your opponents cannot close the gap between
you and them without taking massive damage from the turret. That extra buffer zone that you have may make it unappealing enough for your opponents to call off a tower dive."

"The third way to defend tower is to call upon outside help. Examine your opponents playstyle, and if you see any sudden changes in playstyle (they switch from freezing lane to pushing hard), then you can expect a dive happening soon. pop a ward in your
bottom lane brush, and ask top lane for a TP gank, or your jungler for a gank, or that your mid laner roam. With succificient communication and cooperation, this method of preventing tower dives may actually convert into a kill in bot lane, or something of the like."/spoiler]