Well I got into Gimp because I did have experience with other paint programs in the past. There are tutorials you can find and books as well. But with most programs you simply have to get in and learn it to get the most out of it. I found that the Gimp Shop plugin made it more of a painters program. There are quite a few groups here dedicated to GIMP so you could try asking there for help.
Corel isnt free, but there are probably trials for it.
MyPaint, imo, is one of the better digital drawing applications because there is little between you and drawing, as far as the interface goes. You basically open it up and start drawing. From the start, you basically just need to select a brush and go.