When the RKC was said & done I had at least seven blisters on each hand, my wrists were rubbed raw from friction burns and the backs of my legs were severely sun burned. My hands, wrists and legs were miserable on the 6 hour drive home. It took nearly two weeks for my hands to recover.

One stupid mistake I made was using duct tape on my hands. I had already developed blisters at the bases of each finger and decided to cover them with duct tape. The tape rolled up during snatches, the adhesive stuck to the kettlebell handle I was using during the high rep snatches. The handle became very sticky and tore the hell out of my hands at an accelerated rate. The blisters that annoyed me the most were the ones that developed in the creases at each finger joint and the outer edge of pinkey fingers.

Frequently practice lots of high rep ballistics before attending to accustom your hands to it. Learn what develops blisters and then avoid it.

Practice with Dragon Door kettlebells to get used to the handle size shape and texture.

Work on your technique so you lightly hook the handle on swings and snatches instead of forcefully gripping it.

Manage your calluses. Bring a pumice stone or callus shaver to use on your hands the night before each day of the RKC. Pay attention to all the calluses you develop even the one's in the creases of your finger joints. All raised calluses are likely candidates for becoming painful and blisters.

Wear a fingerless cloth glove on each hand during high rep swings and snatches ... you can make one out of a sock. Bring extras and keep them in your bag. Buy soft socks that wick away moisture such as adidas or under armour. These felt like heaven between my skin and the kettlebell after I'd already incurred severe blisters. I wish I'd have worn them the whole time and possibly prevented the blistering.

Check your hands often during the RKC after sets of swings and snatches.

If you do get blisters do not cover them at night while you sleep. If covered they will stay raw, moist and won't heal. Better to let them air out and dry. Raw, partially torn skin tears much easier on the second day than dry skin.

Save Your Wrists. During the hike pass on ballistics the inside of my wrists receive friction burns from rubbing against the material of pants/shorts. These friction burns become very irritated by sweat. Prevent this with high rep practice in advance and discovering what material works best for you. I'd also either tape my wrists or wear large wristbands to protect those areas of the inner forearm that rub during the hike pass.

Finally...Sunscreen.
Be sure to bring your own and use it liberally on exposed skin, especially on your legs. I saw a lot of severely burned legs during the June RKC, mine included. You'll spend a lot of time on your stomach outdoors exposing the back of legs to more sun than normal.

The RKC cert is difficult enough without annoying torn flesh, burned skin to contend with.