Same as paco, I like a steepish approach, but slow with power on so there isn't a big embarrassing suck at the end.
Also keeps you up out of the possible turbulent downdrafts on the lee of the hill.
Approaching along a ridge is a good idea rather than over the valley between two ridges, because if you have to turn away you can just 'fall' off the side of the high ground - obviously a good escape route is a must.
I was also taught, and like to use, a 'gunsight' technique - ie from the start point of your final approach, sight over the crest (if possible) and pick a point on the far valley floor that you can line it up on, like a gunsight. If you keep the two points superimposed, you will be flying down a constant angle.
Lack of horizon can be a problem, so you kind of have to work backwards and check your airspeed vs. ROD. vs. power (and cross check on the AI if you've got one) to ensure you're not getting sucked into some weirdly steep or shallow approach by the optical illusions possible with hills around.
That's a few that I use, anyhow.