There's some good information/tips posted in this thread. I am based at Front Rage (KFTG) and took the mountain course last year. I learned a lot. I got my rating in OK - where, well, they claim some kind of hills, but, really that's just a pile of dirt or a terrace. If you are going to be operating in, near, or over the mountains, I highly suggest the course. It's hard to get into as it fills up quickly, but, if you also do the flying portion counts as your BFR.
Some of the topics that struck home with me were:
Ground Portion: survival, weather (and lots of weather), and details on sectionals.
In the air: How to safely fly a ridge line, approach a pass, finding "free lift" by riding the updrafts on windward or leeward side of passes, how my plane performed at those altitudes, how planning on paper doesn't equal in the air.
When I landed at Leadville (KXLV) - it was fine but - the takeoff roll lasted for DAYS! At 9,933' of field elevation a normally aspirated engine doesn't develop a lot of power.
Good luck with your flights and your training!
Dean