Bonk:
Participate in a postcard exchange (if you haven't already) and see how many different combinations are used, and how many seem to work out really well.
That is just to gain perspective.
If you can, try to find a real, living, photographer who has a preference, and will show you his/her work, and give you feedback. Then, unless the components they use (film and developer) are truly weird and unobtainable or expensive, emulate them for a while, see what you can accomplish with informed feedback, and go from there.
It's fun!
FWIW, I like Plus X, and HC110 H.
Matt