When our dogs are learning new things we have to remember there isn't just the mental component of learning the exercise and command but also the physical component to consider.
A dog must be fit, flexible and strong enough to perform what we are asking. Sometimes we have to break our end goal down into smaller goals and build it up slowly.
Dogs will naturally have a weaker side and a stronger side which can affect how they do exercises. They often drift away from the weaker hindleg so if you find your dog's hindquarters are veering to the left when walking in a straight line or asked to step backwards this could be due to weakness in the right hind.
I always reiterate how beneficial and important it is for dogs to be able to do exercises in both directions. If you have taught you dog to give paw, make sure they can do it with both paws and if they always spin to the right teach them to spin to the left. If they have difficulties it could be worth getting them checked by a physio to make sure there are no physical issues such as muscle tension that is inhibiting their movement.
As always it is great to teach your dog new things and have fun. Don't get too hard on yourself or your dog if it doesn't go right to start with but treat it as part of the learning process and analyse why it went wrong.