I learned a lot from tackling challenging projects for which I had a great deal of interest. For example,
this was one of my very early projects. I struggled a lot with yarn overs, increasing and decreasing, making bobbles, picking up stitches, etc., but I stuck with it because I was in love with the pattern, and by the end, I felt like I had leapfrogged from beginner to intermediate knitter! And for just messing around, I often tried various techniques from
Knitting for Dummies just on swatches or little things like wash cloths or small bags while sitting and watching T.V. or listening to music. I got really good at figuring out how different stitch patterns worked with different yarns, how to do lace, how tension works, how to neatly work in ends, etc.