Assuming it's a gas engine. (diesels are a different game)
Generally start by putting it in the same gear you rode up the hill in (assuming the downside is a similar slope). Yes, the engine will rev but unless it's redlining the engine, shouldn't hurt anything and the reving will provide some engine braking.
If it does start to go a bit too fast for comfort, use short but firm braking followed by releasing the brake entirely. That will allow the brakes to cool down between applications. If you just apply light braking, the brakes will overheat and then when you do need strong braking, they may not work.
Obviously, watch traffic and curves so you can adapt.