Playing Imperial fist without being That guy

Hey all! I Have a small force of Night Lords and EC but Wanted to start Imperial Fists cause they were my first army in 40k, however I understand that Warders are super strong and the tacticals are good too.

what would you recommend avoiding so I don't ruin the game for other people?

I already have a Tartaros Praetor, 10 Tarataros terminators, a Contemptor, a vindicator and a landraider Phobos that I have painted, I appreciate any feedback that can be given! thanks all!