This is just the way I play this guy. This is a work in progress but I will start with this and you can try it out.
I max Sleight of Fist first and skip the ulti until 10-11. The reason is that you don't really have the mana pool to use it very much and since you can harass relatively safety and block magic damage, you don't need to escape if you just play smart and spam sleight of fist from a safe distance. If you want to gank, go ahead and put a point in it earlier, but I don't think its worth it, until you are a higher lvl. You can still gank without it if someone else stuns.
with your starting ring of Basilius you can spam this skill every time its off cooldown from the beginning. The enemy will not be last hitting safely and by lvl 4 you can do it every 6 seconds from a safe distance, which racks up damage really fast.
to gank without ulti, wait for a teammate to initiate and do a quick slight of hand and then continue in and Searing Chains them to stun, and then pop your Flame Guard and right click and use slight as hand until dead or you or they retreat. You can pop Flame Guard before Chains if you want to help clear creeps for you Chains
once you reach lvl 10 get your ulti and 10 and 11. I like to use this not to gank but in just regular team fights. when you start to group up, throw a remnant into the woods to spot ganks coming. Then throw your remaining remnants behind where the fight will be and one in the the middle of the fight. Don't waste them, they aren't usually gonna win you the fight if you weren't already going to. What they are good for is when everyone gets low from you teammates and your sleight of hand spam, then if they try to head back, zip over to the one behind the fight. If they want to stand and die, zip to the one in the middle of the fight, and if you lost, zip to the one off in the woods.
If its early enough and you choose to get it at 6 you can throw them all in one place, for me usually between them and their tower, where they will retreat to when I show up. The reason for that is if you are hiding in the woods and the enemy sees you throwing 3 remnants on top of them, they are just gonna move away. If its just one, they might not have time to run, but you aren't gonna do significant damage to them.