When learning new knitting techniques, I find it useful to practice on objects where the recipient may not notice or care about a few flubs here or there. When I was learning how to do increases and decreases, I practiced on catnip mouse toys for my two spoilt cats. They love em. And they don't mind that the shaping is a bit wierd. They got toys, I got to learn new stiches.
I've recently taught myself how to cable and practiced knitting with novelty yarns (FunFur and Boa)...once again by turning out projects for the cats in my life. The FunFur is not recommended for this particular application, as the mouse comes out looking...well, a bit frightening. I can barely make out the ears! The Boa yarn resulted in better looking mouse - fuzzy, but not too fuzzy. Mouse pattern was from WendyKnits.