I've been knitting for 10 years, and am an eternal beginner because I only do 1 project a year (or every other), usually in winter, so I know what you're saying about enjoying the process, but also lots of mistakes being involved.
This year I learned about a wonderful thing- the lifeline! If you tend to make a lot of mistakes and do a lot of frogging (ripping out), it saves tons of time and frustration, because you only need to undo a small amount.
I prefer to use a thin, slippery thread so it doesn't pull at the existing knitting, which I've had problems with when using wool yarn, especially thick.
Below is a video link for you about lifelines; there are many others online, but this is one of the simplest and clearest demos. Hope it's helpful!