Try doing things like flyering at Universities and Colleges, try handing out cards at bars.

I personally have cards with me at all times, and being a card-carrying metal head, I tend to meet up with all sorts of guys at shows and other places. When guys find out what I do, a lot of them are totally interested in modeling... They usually sober up the next day and chicken out, but not always.

Oddly enough, straight guys are more interested in modeling than gay guys... so don't just advertize in gay publications, and you might wanna make sure that the ad you've got spells out what they'll be doing at the shoot... if they're not sure if they'll be doing a solo jerk-off or having sex once they get there, they might be less likely to pick up the phone, and you also might want to make a small web page with some information about what you're looking for as well... guys will be more likely to check that out than make a call.... and give them the option of emailing you with a picture of themselves... for the guys that are a bit scared of getting rejected for whatever reason, it'll be easier for them to email and forget about it than to show up and have you say "no".