I'd like to go with 21/0/9 because of
Offensive:
3 in Deadlinessfor more early game crit.
1 in Cripplefor improved exhaust
3 in Archmage's Savvyfor better heal in bloodlust both early and late game.
4 in Alacrityfor more AS
3 in Sunderto increase your dmg.
3 in Brute forceto get some dmg early game which means your crits will hit a bit harder.
3 in Lethalityis a must for tryndamere. Your crits will hit a bit hardet with that.
1 in Havocfor also more dmg
Utility:
3 in Perseverencefor more health reg early game
1 in Good Handsbecause there is nothing else in utility to take :D
4 in Awarenessbecause you should solo lane and this will give you more exp which is great early game
1 in Greedfor a more gold early game.

9 Marks of Malicefor more crit early game.
9 Glyphs of potencyfor more AP (As i told in masteries part, AP is really awesome both early and late game for better heal in bloodlust!)
9 Seals of fortitudefor more early game health.
1 Quints of potencyfor even more AP and heal
2 Quints of desolationfor more dmg overall.

First start with Brawler's glovesand 2 health potions.
Brawler's gloves is a must because you really need crit for dmg and stacks on bloodlust.
When you are going back you should have enought for Greaves. And if your even better you can get your zeal.. If your doing bad in your lane get an Avarice Blade.
Go lane again and maybe gank someone bot. Next time you go home get the +18 Crit itemor if your doing good finish Phantom Dancer. Then you should get the +12 Lifestealbecause you have hard dmg but not that much health. Get Infinity edgeafter +12 lifesteal. Finish bloodthirsterafter and get another Phantom dancerfor full crit. Then get another bloodthirsterfor big lifesteal and dmg.

Berserkers greavesPhantom DancerVampiric Scepter

Early game you take bloodlust for dmg and heal. 1 point in slash for a "get away" AND a chasing spell. lvl 4 Mocking Shout for early game kills. I max out bloodlust first for massive heal. Then i max out slash and at last mocking shout. Always take the ultimate when u can (6 11 16).

Flash and exhaust is most likely because of:

Flash: Double blink is always awesome.

Exhaust: for more slow and if your having hard time with melee dps'

Optional:

Cleanse: If you hate being CC'd you can go with this too.

Ignite: If you think your target is always lucky go with this. It's good in early game but not really late game because you shouldn't have problem finishing them.

Ghost: Can be used instead of flash, but i like double blink more.

Last option i ever heard of is
Heal: It's a good "combo heal" with bloodlust. It's useless lategame but good for some early game kills.

Pros:
On of the best DPS champions.
Fun to play.
Can be a bit tanky with his ultimate.
Both easy early and lategame.
Awesome slow spell which also decrease others dmg
Probably more but can't find them right now :P
Cons:
Useless if he get's stunned while ultimate.
Can't find more now, that's just how awesome he is.

You should always go top. Normally to be sure type to your teammates that you will go top.
If your playing against a squishy hero it should be no problem to farm and get a kill. If your having hard time top just stay and deff your tower. At lvl 6 you can get your first kill. If your enemy is close to your tower, slash into them. Then they will probably try to run away. Then use your Mocking Shout to slow them. If you can see they are running away use your exhaust to slow them again. It should be really no problem to get your 1st kill.

Please rate (and comment). Tell me what's bad and good about it. If you want me to add something tell me :)
I play on EU as the name JHMark