Normally I just run through catching pokemon as I go along. I've always just done that.
However it does mean pokemon that appear later in the story never get a good chance of being in my team. So this time around I'm going to be trading in some eggs when I first get the chance and just choosing my team that way. Partially at least, two of the pokemon I want on my team actually appear early in Pokemon Black/White 2. The other four I'll be trading in.
I think I might abandon my starter for the first time too. I'm just feeling a change is needed.