I've never blind bought or traded.
And now with VG collect I have my wish list with me everywhere. Be it a flea market, retro store, forum post, whatever. I consult my wish list. Keeps me from buying crap I already ruled out. Keeps me from buying gems I've forgotten I have already!
I regularly surf, post, ask, watch, and read to find out what new and old stuff should be in my wish list.