Could I maybe have transmonster tips???
Rather than screaming when startled, try getting yourself to hiss/growl instead! Watch slightly scary videos and force yourself to growl during the disturbing parts more.
If you can, get dog toys or other things meant to be chewed on, and bite them a ton! This can train in an oral fixation, like how cismonsters have!
Try doing quadrobics (walking on hands and feet) more than bipedal walking! If you need, use gloves to cushion your palms. If you do it with your fingers curled, biker gloves have knuckle padding!
If you wish to walk bipedal, then get on your tippy toes, and bend your knees slightly until you're around the same height you'd be normally when flatfooted, this makes you look more animalistic and "beastly".