Not Updated For Current Season
Lucian is just so strong right now. The recent "nerfs" didn't do anything much to stop him. He has a strong early game which carries well to the late game. In teamfights you can have your Relentless Pursuit up every few seconds if you manage your Lightslinger well. This means that you can dash around constantly, getting loads of your Lightslinger double autos off.
Furthermore, if you take the Korean build, you will shed through the enemy's armour easily. Making him good against tanks. Basically he's freelo.
I personally always use armor pen marks, armor seals, magic resist glyphs, an AD quint and 2 AS quints. However if you want to you can just take the standard ADC runes as they work perfectly fine on Lucian.
I take Armor Pen as I find it stacks well with the Youmuu's Ghostblade and The Black Cleaver. Armor and MR is standard but you can exchange the MR for AS. I like to have an AD quint to give me an extra AD boost, and AS is needed on most ADCs.
Early game you want to be poking whenever you get a chance, making sure you are aware of your mana. The most important thing to do early however, is farm. Aslong as you farm and don't die then you will win the majority of lanes. Of course, getting kills is great, and you want to always be in a position to help your support get a kill.
A great tip to get an early kill ( especially with a support such as Thresh ) is too hit the melee minions and kill them as quick as possible pushing the lane slightly and gaining an XP advantage, when the second wave comes you want to kill the first 3 as quick as possible again which will give you level 2. Off this you can engage and hopefully atleast get a flash. If you only get his flash tell your jungler and get him to gank. Otherwise it's an easy snowball with a kill that early.
At this point you should have your Youmuu's Ghostblade and The Black Cleaver, you will be able to do tons of damage with the armor shred and just pure AD. At this point you want to be looking for kills with your support, make sure to communicate with him to prevent any confusion. But make sure you are still farming. Another thing to keep in mind is at this point you might start getting some small fights, or maybe even a 5v5. You want to be aware of the map and be ready for any of these to breakout and help your team.
However if you are losing lane, you will obviously not want to look for a kill unless you are 100% sure you can get it, you can still play a better late game than the enemy ADC.
At this point you want to be grouping, taking objective and helping your team. I've seen alot of ADCs who have no idea how to teamfight. They will just get insta-bursted and be useless. You deal sustained damage so you don't want to pretend to be an assassin like LeBlanc.
No, you should be in a position where none of the enemies can get to you easily and close to an ally that can peel you if possible. If you like going in melee range then I'm afraid ADC isn't the role for you. Of course there are times when its acceptable to not be in the backline but as a general rule that will win you games stay in the backline.
[Diagram of a typical tf formation soon]
I hope you learnt something reading my guide, if there is anything at all that could be improved leave a comment and I will be more than happy to add it.
Thanks so much for taking the time to read this, enjoy the FREELO.