You are correct in recognizing that there is a lot of free advice out there, some of it is excellent, but much of it is as good as what you paid for it!
With the entirety of the internet at your fingertips, you should be able to find someone whose work speaks to the kind of photography you are interested in. Then visit their site to see if mentorship is something they offer. Many of us here offer workshops or portfolio reviews or one-on-one sessions.
I can recommend the services of Brooks Jensen - the person behind the LensWork site and publications. He offers a 40 minute and 60 minute portfolio reviews
Otherwise, search for someone in your local area you can work with or go shooting with. Take a workshop with a photographer you respect (start local and small rather than the $1000+ workshops) or take a Continuing Education course at a local college or university. Students who take those courses know right away who the good instructors/photographers are. Or search out a commercial photographer in the area whose work you respect and see if they offer either workshops or tutorials.