Not to slight Moriouce's suggestion, but I'd suggest getting to know the Codex just a little bit before buying any models (not that you can really go wrong with a couple Tacs and Devs). I fully support the rule of cool, but with 4k+ of Blood Angels a lot of my cool models hang out on display while the more effective models play the game. The Space Marine book caters to pretty much any unit preference, and there are three options for Troops (Tactical marines, Scouts, and Bikes) which can greatly effect your purchasing choices and other unit selection. It's a ton of information to take in, but once you get the gist if you mosey on over to the Space Marine Army List
section of the forum us Heretics can help you sculpt a list tailored to your favourite models and with an eye on strategies that you might not yet see even reading the book a few times.