Hi bluebalti, welcome to this madhouse.
I haven't been here long enough nor have I tried enough different bases to recommend anything, really, but I'd suggest you try out a proven combination of base gravy, mix powder and recipes to go along with them (that reference these base gravies and mix powders).
That way you should have a good result the first time around and can then experiment more next time if you like. I personally started with Cory Ander's (CA) recipes and the results were/are excellent, if that helps. But there are many other excellent recipes (and many talented cooks/chefs) for just about anything on this forum.