For early game you have to play smart I always get the vampiric scepter but if you are not careful you can run into some very poor situations just be careful around ranged champs and work on keeping yourself alive. Only engage other champions if you have a good partner and are certain about getting the kill. Early game for Tryndamere is important to last hit creeps these lil kills not only get you money but stacks for your bloodlust which will keep you pumpin in lane til at least 6.
Once you hit 6 you should easily have enough cash for your ninja tabi and maybee if playing well the start to your first PD (Phantom Dancer) with the zeal. Now you can even go into the jungle and get some buffs. I find that getting the Lizard King buff will severely help on getting enemy kills since it gives you an extra slow and improved dmg. Work with you teamates now and keep trying to build up to the PD.
Your late game basically starts when you get your PD and your first item toward the Infinity Edge which should be the B.F. sword. Trust me go with it first the damage output that it enables you is insane and makes your Undying Rage insane. With the BF sword you should be critting around 500-600 dmg making any squishy hero an easy kill. Just be careful to not get to over zealous, their team is still strong together so make sure you are not the first heroe in but also make sure that when you do go into the fight you focus on thier squishies first then more towards the tanks.
Now my last item was not put in and my lifesteal was never upgraded why is that you may ask that is simple. Most games I never get the chance the game simply ends to quickly. The lifesteal however should be upgraded into a malady if the need arises which is the players call and I have had to do it many times. That last item slot is also a good play to put a defensive item if it is needed to deal with to many stuns/slows enemy spell casters can greatly inhibit tryndamere. By the end of this build I am normally able to crit over 1000 no problem and even most tanks will run from you with out even putting up a fight.
NOTICE TO ANY:
I see alot of players going into mocking shout much later in game. Go into that move as much as possible you only need your spinning slash as a chase/flee it does not do amazing dmg ever but however mocking should causes enemy heroes physical attack dmg to be reduced by a large amount so in any team fight that breaks it is a good idea to pop mocking shout even if they are not running it may in the end help your team to finish them off with taking the least amount of dmg.
Hope you enjoy the build plz comment :)