Start out by killing blue and reaching lvl 2. Most likely you will have someone soloing top quickly get deceive use a hp potion and go kill an enemy up top for first blood. (if there are 2 kill one by deceiving over a wall using ignite and exhaust and teeming him.)
DO NOT JUNGLE AFTER GETTING BLUE BUFF!
Please rate! yes

Kill minions that are not guarded by an enemy. reach lvl 4 or 5 and go gank for a kill.

now farm to lvl 6 you can now gank by yourself.

Get an enemy to follow you. Run to a wall and press r then quickly use deceive over the wall you are at.(dont try on a enemy 2 or more lvls higher than you.) Your decoy should deal good damage then explode the enemy should be low on health. come out when your decoy is dead and finish the enemy using spells.

farm some more and go assist in team battles by finishing enemies by hopping over walls.

Pro's
Ganking
escape
1v1ing enemies
farming
FLASH NOT NEEDED
fast kills (great kill stealer)
con's
Relies on items
needs to be fed
low on health
focused on in team fights
can run low on mana early game

Shaco should always try to farm where there are no enemies because shaco is no good if u just take someone head on always attack after using deceive. Shaco is based off of farming so kill minions then leave to farm some where els
Always be moving
Use deceive to get away from attaching enemies.

shaco should have ability power mana and attack speed but its really your choice.

Never take someone on head on always hide then pop out using deceive use r key or jack in the box to scare enemies away when they charge(also great for getting away)

using this guide should put you as one of the highest lvls on the field. Try to avoid 5v5 fights or 4v5s. Try to get wounded enemies running away or any that stray away from the battle to farm. This should put you as the dominant summoner. (you can get kills that are near turrets with out a problem if they are wounded or a lower lvl.)