Other than closing your eyes and putting your foot on the gas?
I started driving our MH (only 30') in a church parking lot when it was empty. I got a feel for the turning radius. The toughest thing for me was getting a sense where my Right side was located. I ended up finding a light pole in the parking lot that had a parking stripe close to the pole. Then I made pass after pass getting closer to the pole and watching where the stripe appeared on the MH window. For my rig, I learned if I watch at the bottom of the window, in the center where the center post is, that the stripe right there puts me about 12" away from the pole. So, now when ever I drive in a tight spot, I know to line the center of the windshield up with my right side and I'll be OK.
The other big tip involves your overhang... how many feet between your rear axle and the rear of the MH. This gets to be very important when turning sharply. The classic example is pulling up close to gas pumps, filling up, then pulling forward while turning sharply away from the pump. We do this in a car all the time. But with a big overhang on the RV you can actually slam your rear end into a pump. So, I found a nice long stripe in the parking lot, pulled up so my left side was along the stripe, then slowly pulled forward turning sharply. My wife dropped styrofoam cups where the back bumper was. Then, I had a good sense of how bad my overhang was.
Another tip - in a MH you usually do not have a rear window. So after years of driving a car and looking in the rearview mirror when passing someone... well, it gets pretty tough to know when you've completed your pass and can safely move over. I found a car in the parking lot (parked with no owner in sight!) and then pretended to pass it. My wife indicated when I was about a car-length past the parked car. I was able to identify what that looked like in the outside mirror. That is how I can tell when it is safe to get over, though in reality I usually give them a pretty wide safety margin.
These were the most challenging situations for me. Lets see what others identify!