WADS while using 12345 is very awkward while also having to have my mouse over the enemies to aim so when i'm moving I find I only can cast about half as many skills not quite sure what to do
Get a good mmo mouse like the razer naga or naga hex.. puts all the buttons you need for your skills on the side of the mouse for your thumb.
Takes a little bit to get used too, but it becomes second nature in no time.
Moving while aiming, with a mouse and keyboard, takes a little time to get used to. I usually wind up strafing while attacking.
One thing that might help: mouse over an enemy and hit the tab key. If it works, you'll see a glow around them, indicating that you are now targeting them specifically. It won't adjust your camera or anything, but your single target attacks should hit them more easily and the lock will stay on even if they run off and hide behind something. Note: This isn't a guaranteed target lock, but it helps you aim, and is useful if you're trying to pick off one target out of a group.
I use space bar (forward), B for backup, D for right and S for left. Then I use QWERT for skills 1-5. This seems to work much better for me than the defaults.