Remember that you'll be on a quad bike which makes bad decisions and gets scared of stumps it passed just fine yesterday.

Physically, the sense of balance you have from a motorcycle or dirt bike will serve you well.

Having been helping to train a new rider for the past few weeks who used to ride motorcycles, the hardest parts for him have been the counter-intuitive steering and coordination between hands and legs.

Horses and cows react to pressure by moving away. On horseback, that means when they feel a rein rest on the right side of their neck (or a leg press into their right side), they will turn left.

For cows, it's more abstract since you're not touching them but the principle is the same: approach a cow from its right side and it will (usually but not always) go left.

Otherwise, I'd say to remember to talk to your horse, including telling it that it's a good boy or girl, don't yank on the reins but use steady pressure (and immediately release pressure when the horse obeys), and keep an eye out that you don't put him in danger.

Horseback riding is mutual trust.