I'm having a hard time finding people to shoot here in Spain. I've started asking people for random street portraits but you're right, I need more time in front of the camera. I like the idea of finding a mentor but at the moment I'll try and keep practicing any way I can, which for now is taking self portraits.
I take self portraits all the time to practice and learn. Once you comfortably take good self portraits with 1 or 2 different lighting setups, you can use them on a person.
Then practice self portraits doing something different.
You can not learn lighting for portraiture by only doing self-portraits. There are many folks who want a good picture of themselves. You have to network with PEOPLE and trade off some modelling time for images. You can offer to shoot men, women, kids, couples, folks of various ages, and facial structures.
Besides good lighting techniques, relating to directing and evoking expression in people are important aspects of portraiture and people photograhy.
Los buenos retratos se obtienen a través de las buenas habilidades con las personas.
Ed Shapiro- Commercial and Portrait Photographer. Ottawa, Ontario Canada
Maybe you misread what I wrote ?
I practice new lighting techniques, new lighting positions, new equipment, on myself doing self portraits. Once I am comfortable I can take a good photo with that new technique, position, item, I take photos of people using what I learned doing my self portrait.
I frequently do trade shoots with a team of models, makeup artist, hairstylist, clothing designers. The trade is I give them good photos. They are not there for me to practice and teach myself. Sure, I might try something new on a trade shoot, but that is at the end after I have already gotten many good shots using lighting and techniques I am already familiar with. Familiar because I practiced it with self portraits.