Speaking from experience, unless you're going full on Infantry watch what you spend on Infantry Platoons. Infantry Platoons are going to be your bread & butter in most lists, but they absolutely soak up points. Before long, an Autocannon here and a Commissar there could tab you to be more expensive than a Land Raider.
On that same note, in 90% of lists you'll want a Company Command Squad for Orders, Company Command Advisors and Leadership Bubble. Just (again), be careful of how much you spend on them.
On another note, they've changed how Bullgryn Slabshields work in Errata
. Not that important a tip unless you plan on taking them I know, but worth pointing out GW messing with perfectly good wargear.