Honestly, as someone who used to do some coaching when I was much younger you'd benefit from someone to give you direct feedback. Undead is probably not the race to pick if you're trying to figure out game knowledge as to play it effectively you need to be reacting very accurately. The UD 'pieces' are simply weaker if played in a direct sense by lower level players early-mid game. I rarely fight early-mid game as Undead, I poke and take what I can but I'm often concerned about levels/delaying my opponent's strategy.

Having said that if you're set on Undead you either need to watch players like Happy and try to anticipate/understand their macro/movements or develop a style that's sub-optimal but involves seizing the initiative. Usually that's done by some kind of expansion or all-in attacks. Playing an inefficient meta Undead style at lower level is going to get you rolled by weaker players over making inefficient units like raiders/sorcs/dryads/hunts/grunts/ghouls.