So I would consider myself somewhat experienced now, but only with orks. WAAAAGH!! I have finally committed to doing my ultramarine army, love the fluff color and everything. I decided they have a new book so what better time to start them right? So essentially I will be doing kill team a few times but than working from 500 to 1000 plus. My current army is not much. Just my librarian model ( that I am very proud of

) and two
tac squads. My codex should be here tomorrow and I have read through it a time or two already.
My thoughts for my first 500 mec army
Librarian
5 man
tac squad
With a heavy weapon
5 man
tac squad
With a heavy weapon
3 centurion
The grav cannon variant. I beleive there is a way to her a crazy amount of
ap 2 shots with these guys along with bolter fire.
That should put me around 500 ish I am mainly looking an a few solid purchases. Like what to buy next. With orks I started with oh I have 50 boyz well I want 100 more. So that was my thought process for orks. I'm sure you can tell what my armies looked like. So I am wondering what is a good path to go for ultramarines! Whew rant done thank you for all your help!