Hi everybody , and welcome to my first mobafire guide !
First of all , I think tryndamid is a good farmer due to his ability to sustain very well,that's why you can farm without real problem about your hp in most situations.
In my opinion, you should first of all stack fury as fast as possible at lvl 1 , and you might try to see when you crit , to attack with your e spell at lvl 2 when you didn't crit since 2/3 shots , because it will increase the possibility of a crit on your next auto attack (#tryndabasics)
Farm well and keep your crits for the laner , he should have big difficulties facing you most of the time if you crit him in low levels , because he will have to farm under tower with low hp when you have almost all yours , and you could also last hit at the very last moment , so your creep lane isn't under his tower and he can't get the farm , or he will die.
If he went back early , no problem , you don't need to back a lot and you'll have more xp / gold with your better farm
You should try to farm a lot , and go wraith when you can , because whereas some mids like veigar (i don't realy like to do jungle camps with him) you can easily go to the camp , clean it without loosing too much hp because of your q spell , and go back to lane very fast.
Last , your teamfight should be pretty good because you are tryndamere.
Let the tank engage , and try to dps without being oneshoted , so you can use your undying rage as late as possible , or not if you already killed everybody , because you are tryndamere
Thank you for reading this guide and sorry for the english , it's not my native language