Not Updated For Current Season
Start: grab a dagger and head to your lane. Use your bloodlust to heal as you hold ur position safely away from gank. Dont be afraid to take some damage as this will increase your crit chance and with the increased AP build BL stacks quickly to keep yourself healed. Harass the enemy bots as best you can when your BL stacks are about 7 or 8 hoping they get mad or frustrated and mess up(it sounds like a noob mistake but it happens to all of us).
If you can get a kill great, if not oh well. Just don't let them get the gank on you. Be mindful of hidden bots(in grass or fogged paths).
Once you've got the money, your at least lvl 5 or 6, and got them pushed off your turret go ahead and port back to buy your boots and at least another dagger, try to hold till you can a zeal. Head back out and keep harassing until they are mid-low health then let em push you back and go for the gank (2v1 shouldn't be a problem at this point). Make sure you have your BL stacks up. Jump in with ur slash and just white swing till you get about mid health then blow your stacks. At this point if they try to run shout and slash into them. Keep it up as long as you can then blow your ult once your getting low health. You should be able to catch them off-gaurd and get a kill in. Don't push it you only have a few seconds. then blow your Bl stacks and shout again to get away or claim another kill.
Mid:Get your phantom dancer as soon as you can then go in for another gank and at this point you should be able to get pretty ballsy as long as everything is off cd. Between Flash, your dodge, your ult, Bl stacks, and seer speed your should be pretty hard to kill. You be looking at easy bot kills or easy turret pushes. either way all you want is the xp and gold cause you need to lvl and get your infinity edge as soon as you can cause you do your a straight gank bot. Then the snowball begins. Pick off turrets and bots where you can, feel free to jungle if you have the room to do so oe just push back lanes.
Late: Once you've got your second phantom dancer you should be pretty beast and be eating bots unless you've been feeding. Just keep it up until you have room to push without serious risk and you be able to claim the match fairly easily as long as you keep your wits about you.
only serious drawback to this build if you get off to a bad start and have to play catch up it rly hinges on you getting the advantage at some point and just rolling with it. And it lacks much surv till you can get your bloodthrister in large team battles when ur ult is down.
late game you should be able to 3-4 shot even a tank and get away before the enemy has much chance to do anything about it. I've eaten a whole 3ths team without a second thought.
Your arm pen, AS, and insane crits should make you a killing machine. while flash, 40% dodge, roughly 165% movement speed should make it fairly easy to get outta tough situations. The rest is simply learning to time your skills so that you can effectively gank.
THIS IS A VARIATION OF http://www.mobafire.com/league-of-legends/build/tryndamere-hack-n-slash-654