Ok so basically, everyone knows Tryndamere, the OP, right click and win can't f***ing kill me champion right? Wrong, they think they do, and whom ever says that it takes no skill to play him, well, i welcome him to try using him against a team that knows what they're doing [aka knowing how to counter him, because honestly you can play any champion and dominate so long as the enemy team has no idea how to counter your champion x]
So, this is my build, I do have to say that you will be next to useless until you reach level 6, and will be quite squishy unless babysitted by a healer.
Being able to last hit like a boss is a MUST. Tryndamere is one of THE MOST item dependent champs in the whole game, and due to the nature of this build, and the champion himself, you need to at least have Zeal + Boots to be effective in combat [if you're using my rune build you already have +46% crit dmg just from the runes, so with Zeal you get a descent amount of crit chance to do quite a bit of damage, especially to squishier heroes around level 6]
I suggest trying to get at least one kill around level 6, because as i mentioned gold and items are really needed in order to play Tryndamere well, otherwise you'll just end up running into a team/solo fight, doing no damage, and using your ultimate just so you can MAYBE run away by spinning through a wall, which does no one any good.
That's my little introduction... Now onto some details about his skills!

I take this skill on level 1 immediately just so that in case i over extend on my lane whilst farming, due to the fact that i don't use flash with him it's my only escape mechanism early game.
Damage wise, it doesn't do amazing damage, honestly it's mostly there for jumping out of walls to initiate, or to be used as an escape/chase mechanism. Also a great way to last hit champs if you time it right.

This you MUST level up first because it's a heal, that can help you survive after exiting Undying Rage, just so you don't get killed by someone who chooses to chase you, or by some minions that are attacking you when you're down to 1hp and are inches from dying.
It's also a great way to stay in lane, increases your damage output, allows you to heal after a minion wave, it's basically your bread and butter, so max it out!

This you skill you get whenever you can't get Bloodlust... It's also a very important skill due to the fact that it will allow you to chase down your targets, and lower their damage output if they turn to fight you, so the skill is also a must, but your Bloodlust must be leveled 1st due to the fact that it will help you survive, and farm.

Get this skill whenever you can, it doesn't change it's core time of 5 seconds of invincibility, but it increases the amount of Fury you will get when activating it, allowing you to have more to consume with your "Q" upon disengaging your opponent/s.
Also prediction is a must with this skill, you're not supposed to activate it when you have 500HP, but when you're around 100HP so you can stay and fight as long as possible.
Always take into account who you're playing against and you're getting targeted by, nukes can throw you off balance, so you need to know if you should maybe turn it on when you have 1k HP to survive, or use it at 10HP, wasting your ultimate when you're not focused will end up getting you killed once they do start beating on you.

This isn't a jungling build... BUT! Sometimes if i have problems farming in my lane, at level 4 i will go and do a walk through the jungle killing everything but the red and blue buff, it will give your partner some additional gold and xp and make it easier for u to get some yourself.
After level 6 you should be able to get the buffs as well, and cleaning up the jungles is a great way to get additional gold that you will need, so when you can make detours through the jungle as much as possible late-game. If you're getting a descent farm around level 9-10 you should be able to solo off dragon rather nicely.
You'll realize that later in the game you will basically one **** minions, and that you are extremely fast, allowing you to farm 3 lanes + jungle like a boss and be able to jump in on ganks by using your spinning slash + mocking shout.

You aren't a pro just because you can stay invincible for 5 seconds, no you can't solo 5 champions on level 6, no you cannot tower dive when someone is at full HP, get the kill and live. However, all the above changes late game...
After infinity edge, getting life steal is a must, it will allow you to postpone your ultimate as much as possible, and keeping allowing you go quickly heal up from creeps right after a fight.
Early game you're still dependent on your team to do some damage, or at least be present, later if you get enough kills, and the enemy team isn't fed too much, you should be able to solo even tanks with 5 shots due to the fact that with Inf. Edge + Runes + Masteries you have i believe something over 300% Crit. Dmg. giving you roughly 1k crits consta-crits with inf. edge + phantom dancer.
After finishing off Bloodthirster, feed it with creeps to get it stronger, and after that the only items worth getting is Stark's Fervor, or some Last Whisper if you're playing against a tanky team, because you need to add some more attack speed to dish out as much damage as fast as you can, not giving them room to take enough HP away to make you actually use your ultimate.

That's it, here are some saved games from me playing Trynda with this build as proof that it works, at least for me, and... enjoy