Experienced mountain bike ladies, I need some advice on how to handle some terrain.

I've been riding with DH and our friend K this summer, and I'm really pleased with the improvements that I'm making. The boys make me lead a lot of the time so that they don't inadvertantly lose me and, as a result, I'm getting faster and better at cornering. I told K that having him riding behind me was like having an angry mama bear behind me- I was too afraid to slow down!

On that note, there's a couple of local trails that still continue to freak me out. One is a very narrow, very steep path cut into a hillside. One false step and you're in the brush at the bottom of the hill! I can handle the gentle ascents and descents along the edge, but the steep stuff near the edge freaks me out.

The other is a series of switchbacks that wind through a gully. The switchbacks are gradual and shallow near the top, and become progressively steeper and sharper as you approach the bottom. The short steep descents are ok- it's the turning at each end without crashing into a tree that's the problem. I'm getting better at it, and able to go further along than I used to, but I still get to a point where I don't think I can make the turn without tumbling over sideways.

So.....any suggestions for how to navigate this terrain, or exercises that would help me that I could practice in the back yard? TIA!