@rgdouglass Another huge factor when just starting out is, your NERVES need to learn how to actuate your muscles efficiently.
The major (relatively huge) gains a newbie makes isn't from muscle strength, but from
learning how to actually push, with the same (low) muscle mass. Those nerve synapses get strong faster than the muscle can.
Example, someone that use to lift but left off for YEARS, can pick it up again relatively quickly. Those old nerve connections just need to be dusted off a bit. They'll be on their way to bulking up much faster than someone just starting out, because their nerves have already learned how to use the muscle they currently have more efficiently.
That doesn't sound like OP's problem with shakiness after a workout, just a side note about shaking
while lifting (at first).