Vampire is a bit tricky in the beginning, but becomes a lategame monster.
Tn the beginning, you'll have to use Bloodpools and maybe kill a bit of popcorn to gain levels; early level vampires are relatively weak. The trick with the vampire consists of looking for a high health- low dmg monster and using it to heal yourself whenever you need. Be carefull not to kill those; "You can sheer a sheep many times, but only skin it once."
Meatmen are perfect for vampires.
Transmuter: Use Lemmisi to scout a little bit at the start.
Spam Spells with every step.
Try to use spirit sword for easier leveling; Try to emtpy your mana before you trigger spiritsword; unlike the strength potion, it works with your max Mana. Leave glyphs for bossfights.
Other than spirit sword, I've felt the transmuter hasn't much you could leverage in general; you'll have to depend on glyphs, deities, and general strategy for that.