Many might first ask why flash? Well i started with smite and ignite shaco like everyone else. After a while i realised that i played mostly as a fighter with assasin. So once i tried with flash and thats how i got good with him. Flash will make you even harder to catch or to escape from. This is a high-risk/high reward play style so it wont always work but when it works youll be carrying youre team.

Jungle goes pretty basic, but remember the power of this build comes in hand at mid game so dont gank unless youre sure you and laners can kill them. You can also easily counter jungle, but this is a risky act too.
In jungle dont use youre e on them as they can miss theyre attacks what can save you from a lot of dmg.

In teamfights try to be unseen and take out high threats (such as adc, mid laner etc...), but remember to let youre team know as you go because after starting the fight youre the target but if youre team is aware of youre engage by youre (possible) death they can get easy ace as the enemy team tries to take you down fast. Remember that youre assasin! This is where i sometimes fail if youre too sure about winning a fight youll do mistakes more easily.
Heres my 2 favorite ways to start a TF with shaco.
1: use youre q over terrain and hallucinate instantly youll stay invisible and theyll likely kill youre clone. escape after ulting and show up again when youre team engages.
2: show yourself and trick them into a bush by placing youre w before hand will give you time to take few out fast this tactic requires high teamwork and communication if youre team dosnt know where you are and what youre gonna do you cant succeed.

As i didnt show any runes i can say that theyre not needed but theyll still help. Try to take AD runes, attack speed runes and movement speed runes as theyll power up youre chances of killing someone without being seen.

Try to always engage single targets with q from behind as this allows you to do immense dmg before they can see you.
Dont go 1v1 on fighters unless they have no sustain or dont have a lot of armor.
Depending on tank you can take them out but be sure they have to kill you slowly if youre gonna fight them.
Using ult can save youre life from some ults and abilities if timed correctly.
Keep an eye on youre mana as it can for people like me run out very fast.