I think by the time I fight Ridley, I usually have enough missles and health that I realy don't even try to avoid him that much and just fire as fast and rapidly as I can over and over. Just pound him. I'll try and avoid his tail swipes and ground pounds as I can and not be completely stupid but I'm more concerned about aiming correctly and keeping a constant barrage up. Even if he grabs me in his claws, I just use that as an excuse to better aim at him and fire away. I think I usually end up close to death at the end but the point is, he goes down first.
That's my brilliant advice.