The advice for newest model girls: if you’re not comfortable with guys just make photos with girls!!! make your casual content and  save money doing that, pay the trusted photographer that you admire; don’t make partnership with any guy with camera just because you don’t have money yet.  The good oportunities will appear in future for you ~
Mainly I look at their works and I try to get some reviews from girls who have worked with them. And of course it's very important how they approach and behave!