I think that I understand - not to be glib but you want to buy your bicycle a Christmas present.

What's your tool box look like? If you have the commonly needed tools like a GOOD cable cutter, I'd suggest buying yourself a derailleur hanger alignment gauge. Derailleur hangers are easily tweaked which will cause your shifting to so strange things. The more rear gears you have the more closely spaced they are and, consequently, more picky about having perfect alignment. Being able to check and align your own hanger can be handy.