For the life of me, I've tried several different builds and I always go for the high ground, but I can't get an archer to do remotely decent damage.
Where am I going wrong?
Any help or tips would be much appreciated!
Probably not keeping your weapons level in line with your character. I used to think that 2 level difference was ok, but there are some steep difficulty curves so I would suggest trying to keep your weapons within 1 level of your character's level. Also a crossbow uses 3 AP which makes them pointless, a bow is almost always the better choice in EA [on release Xbows are 2AP with less range but more accuracy than a bow which has more range and less accuracy]
To further help you we would need more information on your build and stat allocation and talents. I have built monster rangers with just one point into huntsman. It all depends on how you want to play.