Well, this is my first guide, so don't hate too hard. Just try it if it sounds interesting

WARNING
I AM A ROAMER. This means that i gank alot throughout the laning phase. This is very beneficial to your early game farm of players, so try to gank often, yet still stay in the same level range as everyone else.

I don't want to go on and on about Shaco's GOOD stuff. If we focus on the BAD, we avert our attention onto these problems, and therefore solving them.

SQUISHY-Shaco has NO health, so he usually gets destroyed in teamfights.

SUB-PAR FARMING- He has no AOE abilities besides his weak boxs(Unless you farm with your ult..?)

HOW TO FARM:
Learn to last hit- play DotA, play a couple Co-op games, maybe even custom. But last hitting is too crucial to the game to be overlooked. However, if you do suck at last hitting, then this Tiamat tactic may work for you. I personally don't have trouble farming, and the Tiamats make me farm minions like Malzahar.

GANK ENEMY JUNGLES AROUND 3-4 MINUTES:
Of course, only do this if you know how their jungler operates. If this gank does work out, you have successfully messed up his jungle, and consequently removing him from the game for 3 or so minutes while he regains his jungle route. Always be checking your mini-map. While your ganking, and you notice that someone is missing on the enemy team, QUICKLY run, because they probably have a bait/counter gank set up to catch you.

To start, i like to get a doran's blade. This provides so many stats, and is crucial to your early game. After that, i like to get boots 1. Right after, i rush 2 tiamats, and if possible, i upgrade my boots to boots 5.
CHECK: 2x tiamats, 1x boots 5
Then i usually go for a starks fervor. It has more benefits than some of my friends, so i always make sure to nudge it into my lineup. Afterwards, i pick up an Infinity edge and a last whisper. If you happen to drag the game into late game scenarios, feel free to sell off the tiamats for 2 phantom dancers. The last 2 additions will drastically improve your damage output.

Everyone's play style is different. That being said, this build requires you to gank efficiently and often. Without ganking, you begin to feel like a Garen with Mana... Useless.

The Tiamats come into play after you finish your ganks on lanes. With only a few strikes, you'll be able to farm minions so well, it'll be like you were in lane the whole time. Tiamats also provide great regen in both mana and health. This is not to be overlooked. EVERY BIT COUNTS.

Now, am i the best Shaco ever? NO. And i will never be. BUT, if you look at my recent history (As of May 3rd 2011) you'll see that i went 21-0-9 in a ranked game with this build. Some say its a troll build, i don't care. I call it fun and good.

Exhaust and Ignite are my personal 2 favorite ones for this build. Flash is almost pointless, because Deceive can do anything Flash can do, so it is a little dumb to have 2 flashs, while wasting a summoner spell on one of them. Ghost CAN be switched out with exhaust, but the Boots5 should get you around places well enough, so i take exhaust instead. Exhaust is so helpful. It helps first bloods, second bloods, third bloods, escapes, chasing. It is just too beneficial to Shaco to turn down. (in my opinion)

Hope you enjoyed!
Your fellow gamer,
Hydro