I'll approach this 2 fold, from mare owner and stallion owner's perspectives. I use Arabian Horse World & Arabian Horse Times magazines, to get an idea of what I like and what does my ideal Arab look like. I look at EVERY e-blast that comes in my inbox. Then I find out where they'll be showing and I go to the shows to see them, especially if they're standing somewhere that too far to visit a farm. Then I look at their foals, if they have any. Then I meet with the owner or manager that's standing the stallion and get all the facts on costs, charges and a copy of their contract. Do the ship semen? Cooled, frozen? Not at all?
WHO is their trainer? I always check that out because some guys are a little to handy with a needle and those steroids and Regumate can screw up a stallion's fertility. There are stallions I love that take 2 or 3 SEASONS to settle a mare because their sperm is junk. I won't get near those.
So, I start with e-news and magazines and what I see at a show, but that's only the beginning. If the owner isn't easy to deal with or professional, NEXT! There are too many nice studs out there to waste time and money on one who has issues because of customer service.
And, I certainly wouldn't own a horse who HAD to pay his own way as a stallion, IN THIS ECONOMY, because it really seems to be that unless you're in that top 2% OR unless you're giving away your breedings, you're not going to be selling many breedings.
Mare owners have cut waaaaaaaaay back on breeding right now. I have 3 stallions and have not sold a single breeding and one is a champ many times over. By now I usually sell a few breedings, maybe only 2 or 3 but people are making their decisions NOW and it's just not happening. I have mares who have been open for years because of how much I've cut back.