trackstand - pinch the top tube with your knees for help until you get better
skip - lift out of saddle a little as pedals approach 9 & 3 then press down with rear leg/lift with front
skid - eh, just go to youtube. Im sure there are countless vids up there on this by now

I learned to skip in about 15 min with 49x16 gearing.
I learned skidding in a couple of days since I didnt do it often.