I'm not claiming to be the next Shaclone, but I consider myself way above average on Shaco and he is my main. He is such a fun champion to play with endless builds (mine is the best :D) and endless possibilities. In all honesty, I highly recommend him as a main, as he is honestly the only champion I never get tired of playing due to the fun I get from pulling of The Great Escape in a 1v5 or driving the enemy into insanity by countering their every move! Anyway, onto the guide!

Pros

+Great burst
+Good clear speeds (and sustain in jungle due to boxes)
+Great mobility
+Versatile
+Potential to control the early and mid game by shutting down the enemy jungler
+Massive outplay potential (both defensively and offensively)
+Good 1v1 potential, especially with ignite/exhaust
+Potentially the best ganking jungler in the game
+Good splitpush and counterjungle power

Cons

-Hard to learn and play
-Requires near perfect time management to abuse his potential
-Requires good game knowledge to utilise to full effect
-Very squishy (if you don't build tank or my build)
-Using Q to engage without shields can get you blown up
-Vulnerable to CC if R is not up
-Not a good pick if your laners are aggressive and snowball champions (since your mere presence will dissuade enemy laners from pushing)

This is a guide that I believe makes Shaco great for ranked. A lot of people believe that Shaco is not a good champion for ranked because he can't teamfight and he falls off. I would agree for the most part, but this build gives you way more options for teamfighting as you can jump on the carry in teamfights, make them disappear, and survive long enough for your team to back you up! This being said, the build shines in gold and silver elo, and gets less effective gradually after high gold and towards plat and beyond due to good game knowledge (pink wards etc), but it still beats the other builds at these levels!

NOTE: THIS GUIDE REVOLVES AROUND THE BUILD, THIS BUILD IS WHAT MAKES THIS GUIDE OP, SO IF YOU ARE LAZY LIKE ME FOLLOW THE BUILD AND YOU'LL BE FINE. Now, this is a unique build that I made while trying new things on Shaco. Most builds only allow for full damage, damage and crit, or low damage but high tank. However, all of these builds fall short of something. Damage builds are always useless for teamfights (i.e. bad for ranked) and tank builds just aren't good enough on Shaco. This build gives plenty of damage and also enough sustain to survive a prolonged fight, it is a perfect balance of tank and damage, so you can still make people disappear :D. The only thing that lacks is epic splitpush power (compared to shiv and hydra builds), but its still there.

Shaco is arguably the best ganking/invading assassin in the game. He is also a fantastic splitpusher since you can juke for days and escape any ambushes or angry enemies that come your way. Time management is very important to succeed as Shaco, as you should always be ganking or looking for an invade after level 3. Invading is good because you can use your boxes as wards to track the enemy jungler to alert your team or go in for the kill!

In regards to summoners, Smite is a must take obviously. I really like ignite as my second summoner spell but I've seen people take exhaust for similar reasons (early kills for free). I would never take flash on Shaco because of his Q blink, since when you learn him you should never Q in to fights you won't win so escaping is usually possible with it.

Once the game has started, ward possible invade routes and go to your red buff (or blue buff if on purple side), then when the timer hits 50 seconds place your first box behind where the large monster will spawn, so when it attacks the box you get extra damage from your passive. Keep putting boxes there in the same place until there are 3 boxes down. Now, a lot of people don't exploit the double proc of fear that you get if you place the fourth box as the camp spawns. Doing this will allow you to clear faster and take NO damage from the camp WITHOUT SMITING (SAVE THE SMITE). Now you are level 2 TAKE Q, not E, and make your way behind the ENEMY buff on the same side of the map. Now, when you get behind the buff use your Q to blink over the wall into the camp. Usually, you will find a half health enemy jungler trying to innocently take his first buff after a leash. If this is the case, smite his buff away from him at the last possible second and then attack him before the crit from your Q runs out. If you can get the kill with IGNITE, great! If not, just run away you have his buff :D! If the enemy jungler has started somewhere else, great! Take his buff! Now take E lvl 3 and gank or invade where you see fit for the rest of the game, since you may have a kill and/or the enemy jungler is behind, but try and abuse this early advantage. Note: You don't need a leash from your bot lane using this method, so they can exert massive pressure on the enemy bot lane by pushing immediately while the enemy jungler is being leashed.

When ganking as Shaco, expect an easy kill until you reach high gold and above. You should wait until the enemy laner is almost in the middle of the lane. Then get as close as possible without them seeing you and activate your Q. Use the invisibility time to go behind them and place a box in the their escape route. As soon as the box is placed, backstab them for the extra damage and auto attack them and smite if you have it. Save your E for as long as possible as it is more efficient that way (more slows). If they somehow last your initial burst, your box should fear them and the laner/you will pick up a free kill.

My favourite aspect of Shaco and maybe the most important in terms of play-style is using mindgames to dictate the way your opponents play. If you get a kill in a gank, why not wait until they get back and kill them immediately again? this may make them rage, or make them too scared to push your laner giving him/her a nice laning phase. Also, place boxes everywhere when invading the enemy jungler. There is nothing more terrifying than walking into a Shaco box in your own jungle, as you don't know if hes about to kill you. Use tactics such as these to try and force your opponents around. E.g. force an enemy laner to play passively by camping them (best against snowball champs like Fizz), or dictate the enemy junglers movements by placing boxes in places you don't want him to be (e.g. in the routes leading to Dragon and Baron). Furthermore, your ultimate can be used to bait people in to fights by controlling the clone and hiding somewhere else, but I prefer to use it as a last resort to survive or to make the enemy commit to a fight he can't win.

Thanks for reading, I hope you take your new found wisdom and go and take the rift by storm with this new Shaco epiphany I have bestowed upon you! If you want me to elaborate on anything further (such as any items or enemy junglers etc) just leave a comment and I'll edit the guide and mention you to make it easier to find :))