Be sure you're comfortable with this. Most of the routes are relatively safe, but this is no place to freeze, panic or discover you have acrophobia. The driving requires no extraordinary skill, but caution, attentiveness and common sense are necessary. Check with local sources to learn current trail conditions. Whether your vehicle has a manual or automatic transmission, take descents by using low gears matched to your speed for control.
Brakes are for stopping and emergencies.
Continuous brake use heats them. Hot brakes are ineffective. As well, you may damage them to the point that the rental firm will charge you for the abuse. Mountain weather changes quickly. Sunglasses and sun block are useful as the sun at high altitude is more intense.