I was an artist's model for several years. I loved, during breaks, walking around seeing what the artists were working on. A lot of times they would give me the sketches I liked. Below is a painting that one artist did but he didn't like it (yes, he did it in a 3-hour session). I knew I couldn't afford it but I asked how much and he asked for private sittings. He was working on a series of book covers. Somewhere out there are some weird-ass pictures of my bum and red spike heels and a ray gun... lol
But I got the painting!
Seriously though, if you're not in school but can find a group of artists who have life drawing sessions, go! I loved watching how people progressed. I modeled for four specific groups of artists that were starting and well into their careers, from illustration to fine art. My favorite time was when an artist's cat would come and curl up next to me if I was doing a reclining pose. Although... I do have a few scars from when she was kneading.