This is the build I have been using for a little while now and while I do not play ranked often at all I do stomp players in normal games and in low elo ranked. It gives the perfect combination of health and power in my opinion.

Pros
-If they don't have the entire map warded then they have no clue where you are
-Amazing ganks
-Great at 1v1 at all lvls
-Great at ksing
Cons
-Is hard to escape if you find yourself out of position
-If they have vision wards ganking can be difficult but just go around them
-Crowd control can destroy you

These are the runes that I use but I have not tried lots of others. It lets you 1v1 most opponents at lvl 1 and helps so that you don't die instantly

This is just some of my most recent games with him to show you that it does work.

I have played twitch quite a few games and he is best at being solo top or in the jungle. Do not go bot with him because it's annoying going against champions with a longer range than yours and having it where 2 people can just focus you down since it's generally a support on bottom. The key to playing twitch is map awareness and good positioning. Keep track of who has oracles and what is warded all the time so you aren't caught of guard. Also in team fights be sure to stay back so that you can blast their whole team from a long range with spray and pray. Finally and one of the most important things to know when you are twitch is DO NOT INITIATE UNLESS YOU KNOW THAT YOU WILL WIN THE FIGHT. YOU ARE NOT A TANK OR TANKY IN ANY WAY.

I know this guide is short and doesn't include much info but leave comments if you down vote me and tell me what else I need to put. It's my first guide and I just took 15 min to make it so go easy on me. =)