I just seem to flail about and do nothing. I know it takes time, but i have been trying for ages and cannot find any good moves.

For moves you need inspiration. Watch action movies or other members replays but don't steal.

To dismember you need power and force. If you want to cheat a bit you can lower the dismemberment threshold to 80 but some members look down on replays with lowered dismemberment.

If you want to kick, relax the foot/feet, it makes it easier to DM.

Take some time to gather momentum, conserve and compress it into the your attack limb, and attack. Use ALL the joints in your body, and target Uke somewhere in the center of his body (if he's remaining still and stiff, it's quite annoying to dismember without him running into your attack). Grab him and push him toward your kick or punch - For example, if you're going to kick him with your left leg, grab him and push him TOWARD your leg. It adds to the total speed of your attack and makes it easier to dismember uke.