I suspect that many are like me, and (at least initially) have no master plan. Initially, I would search for interesting bicycles without much regard to whether they fit me, or whether I would be likely to ride them. After a few years, I have made some plans for what to keep, what to sell off, what I'm trying to find, etc. However, the small parts are sometimes an issue. Hopefully you're more organized and disciplined than I am - but if not, you'll learn as you go.