One way to get more confident at machine quilting is to just go for it! I make a lot of baby quilts and that is where I practice and try out new things. Very rarely does something not work out. It may not be my favorite but it helps me figure out how to go about the next one. So go piece a small baby/kids quilt and do something other than meandering (not that there is anything wrong with that!) and see what you come up with. You can always donate it to a worthy cause.