Building an Army and looking for guidance

Hey fellow Fisters,

So as the title says, I'm building an Imperial Fist Army (praise Dorn and The Emperor) and I'm looking for some guidance on selecting units.

for reference, I have been painting minis (mostly 30k Marines I came into ownership of) for about 6 months with the goal of just looking at them, beautifuly painted on a shelf. However I have recently begun playing on TTS and I'm wanting to assemble a physical army.

I made the amateur mistake of buying the Space Marines Combat Patrol with the pushfit models from the Leviathan box. I have made some modifications to the base box myself, but I was curious what others thought I should add and sub out etc. I do plan on expanding it to a 1000pt army to play with one of my friends so that can be the hard cap, 500pt the soft cap.