I've experienced downdrafts that have made my plane fall like a rock. Gaining altitude efficiently is a skill that can take a while to learn. It just takes lots of practice before you can do it well. Some slopes have more lift than others, so gaining altitude may or may not be a problem depending on where you fly. When there are other planes flying with you, use your periferal vision to avoid unwanted mid-air collisions.
Unpredictable pilots end up crashing with other planes way too often.
Fly as crazily as you want when there's no one nearby. Ask other flyers what your landing approach should be for that particular slope. If no one's there to help you out, pick the biggest, flattest, softest part of ground around.