I don't remember the game all that well, but from what I do remember:—
It is easier to do the Red Dwarf Mines in two visits. The top level, where you rescue the dwarves, is much easier than the lower one.
Apart from that, some of the easier quests are
(1) To find the lost Arcomage player
(2) To find the Site of Power
(3) Killing the troglodytes under Stone City
(4) Entering the Faerie Mound (once you can get to it), and
(5) following on from (4), Deliver a letter to the Faerie King. You'll have to go to the Tularean Forest to be able to do this, but that's not a difficult area.
I'd be a bit wary of the Haunted Mansion until you're level 11-12 at least, and you need a decent disarmer if you're not going to spend an inordinate amount of time healing your party.