I think understanding ingredients is a big one. Way, way back when I was in the US doing partial mash brews, I would go to the homebrew shop and taste all the grains from the bulk bins. I would think, "Yeah, that's the flavor I want in this beer, and a little of that..." That's not so easy to do in Belgium since grain isn't sold in bulk, but you could buy 250g bags of everything you can find and taste them individually. You could even go so far as to make a mini mash. As for hops, I still re-read the profile of every hops I have before adding it to a recipe. From there, experience and maybe some advice from the good folks here will get you where you want to be.