Before doing anything with Shaco, I have to tell you that unless you actually main Shaco or play him A LOT, there is a really low possibility of this working for you, as there are many little things that you need to be doing instinctively, but these cannot be taught, only learnt by experience.
His kit might seem quite simple but he isn't an easy champion. Or atleast isn't easy to play him correctly, at fullest potential.

Hellooo
I am McZeddy, playing League since the start of S6, managed to get to Platinum in it and I am currently Diamond in S7. I've been playing a lot of Shaco since the beginning of my ladder climbing - back from Silver.I've got 400,000+ Mastery Points on him. After the rework he didn't really feel the same, but I got used to him with this particular build.
I stream from time to time my ranked adventures - Stream Link
I also have a Youtube channel with some highlights of my League experience - Youtube Channel Link

These are the masteries you can run on Shaco, Fury and Sorcery are both good, I choose Fury some of the times since it is a percentage increase, and we get a good amount of attack speed, so this benefits more.(I also use it because I don't really have attack speed runes) Sorcery is a viable choice as well, increasing your burst damage by a bit.
Fresh Blood is exactly the one you need from the next row.It gives you some bonus damage on your first basic attack against champions, which helps you in ganks when you Deceive into the enemy. It adds up to the bonus damage from your Deceive and Backstab.
Natural Talent is better than Vampirism in my opinion as the damage of this build isn't as much until your first few items, then it gets crazy. Natural Talent better increases this later spike.
I find Battle Trance the best from the other 2 as it boosts your Two-Shiv Poison damage by a lot. Why? You will find out below as it is really complicated to include just shortly in the masteries section.
Next up, Savagery, Assassin , Merciless , Greenfather's Gift , Precision and Thunderlord's Decree are in no doubt the better choices of the rest, the only one which is more of a personal preference is Runic Affinity to Assassin .

Maybe these need videos to be understood correctly. I will be working on that but not sure if I will have the time to finish them.
Whatever, until then you gotta carefully read what I've wrote and if you still can't get it right, leave a comment or contact me.

Right, starting off with the Jack In The Box. You will be using it in these occassions:
- Jungling
- Ganking
- Before fights
- Vision
- Escaping

In the jungle, use it basically everytime you start to clear a camp(unless it's late game of course.
But before the camps spawn, Shaco players are known to put some boxes around them, as it helps for clearing it.
Here are pictures showing the positions for them, with timers:
(Work in progress)

Generally, when you gank you want to get as closer to the enemy's champion as possible. If you still have some invisibility time, position yourself behind them, or rather where you think they will start fleeing towards.(maybe to their close teammate if any, maybe to the closest tower, or a convenient for them jungle route?)It's a bit of psychology, but you have to get used to that.So, when you've done that put down a box, thinking about it the same way - in the direction you think they will be going. If you have no time to put it some distance behind your enemy, don't waste time putting it on top of them, as they will easily walk away and you will just lose potential damage. In that case just start basic attacking.


Before fights, be it full teamfights or a potential flank, jungle stealing, objective fight, you always have to know where to put your boxes. For example, you fight the dragon. Before starting doing that, it's good to put a box or two in the river, or a bit in their jungle. When you splitpush, always box around the lane for an easier escape if the enemy chooses to stop you. Before major teamfights, put boxes around your team, believe it or not they can help loads. They can fear assassins trying to get close to your ADC or another squishy target.And not just for assassins, of course, it could be any of the enemies.

Not much to say about using boxes for vision - have them for wards, ward around, but of course keep an eye on your mana.

Lastly, you should have a habit of placing a box in front of the direction you are going to when you run away from enemies, as it helps for escaping.





Next up, Two-Shiv Poison.Maybe you think "That's point-and-click damage, why does it even need this whole section, I already know how to click on enemies?"
No, it's not.
This ability's usage is key to differentiating a good Shaco player and a bad Shaco player, along with Jack In The Box.
Two-Shiv Poison is NEVER used before your first basic attack on an enemy, or even after it. Its passive works only when the ability isn't on cooldown, so we use the passive first - basic attack every time you can when you fight with an enemy, rather than using your Two-Shiv Poison. Basic attack, basic attack, basic attack. Now there are 2 situations:
- Enemy is low enough for making most use of the execute damage of Two-Shiv Poison.
- Enemy is too far for a basic attack after you were basic attacking him(used flash or some sort of a dash).

Only in these situations you should use Two-Shiv Poison to fully maximize the effect.
Later on with more Shaco experience, you will be doing this instinctively, but until then you should know about it.

I realize that videos would help more, I will try to make them as fast as possible.