Pale Master's fun. Definitely invest in your skeleton buddy, he's the beefiest companion by far, despite the lack of meat. A good way to figure out what kind of gear to look for is to look at recurring themes in the enhancement tree.
PM has: negative spell power, negative crit, negative healing amp, necromancy focus, etc. All very important for a PM to have.
You want at least one secondary element for things immune to negative energy. There's a tier4 ability that lets you strip negative immunity from undead specifically, which is very helpful, but enemies that cast deathward are immune also (as well as a few other non-undead monsters). Fire is a good choice for fireball/meteor swarm. Or electric for chain lightning.
Watch out for "lifesealed" which every other build likes because it's deathblock+negative absorption. Trouble for a PM is that this (and plain negative absorption) actually makes you heal for less.
What expansions, if any, do you have? This month's year of the dragon is a free xpac (other than vecna) so you want to pick a good one. Named gear from xpacs are going to cover all of your bases basically. Feywild has lv 5 and 29 gear, Ravenloft lv 10/29, Sharn 15/29, and isle 7/32.
is my go-to there.