Go out in 30 ft of water and practice your ascents. Stop every 10 ft and hold for 1 min. Dedicate the whole dive to it. As said before vent early and vent often. I have found that raising my left arm, elbow high and bringing it down in the same kind of motion as when making the fart noise with your arm pit works for me. It's all about managing the bubble in your suit. I'm not sure about the whole loosening the straps and belt thing, just make sure everything is properly adjusted to begin with.