RE: keeping steady
Do you start off good and then it starts "wobbling"the more you shoot it?
If so then its just muscle.Your upper body will strengthen up the more you shoot it.
Another possible culprit would be your anchor.
Are you holding it away from your chin or is it snuggled tightly in.?
Like MilDot said,play with your draw length and find a comfortable anchor.
Also dont lock your arm at full draw,your muscles need to be relaxed somewhat.Just give it a slight relaxed bend at the elbow and hold tight to your anchor point.
Dont over shoot to make yourself tired---worse mistake you can make.Alot of bad habbits are made and hard to correct.Shoot a little each day and things will work out great.