When farming as trundle try to stay behind most of your minions only leave their cover to last hit. If you don't Think your going to get the cs from a minion just Q it that way you will get a little health back and still get the cs. If the enemy laner try's to stop you from csing by scaring you off just Q him and walk away.

(This Is the only chapter i'm going to put in this build This is my first build so please don't criticize it to much i would not mind a little Criticism though Thank you. Happy Trolling.)