I found this info in Indoor Rock Climbing Information and Tips! particularly helpful.
8. Climb in an X shape with your hips being the middle of the X. Hang with your arm straight. Your skeleton can take much more of a load than your muscles can. If the heel of your foot is hanging too far down you may notice your leg start to shake like a “sewing machine”. This is very common occurrence, simply apply more weight to your toes so your calf muscle spasm can stop.I made it up my nemesis, the 5.8 Face Plant route and I also made it up another 5.8. I had some false starts, takes and marching orders from Patti who, I believe, said finish the freakin' route (newest and scarier 5.8 nemesis). I was about two holds away from the top when I thought I couldn't make it. Jessica said that her mom does not use freakin' very often. Patti was a firecracker all morning and I did finish the route. LOL.
I was surprised, though, when Patti told me that she didn't feel like an athlete. Okay, the woman is a great rock climber and that, alone, qualifies her for athlete status.
Here's the Dynamic Duo (i.e. my main rock climbing partners in crime) waiting for a route to clear.
And here are my budding calluses:
Corns and calluses are caused by pressure or friction on skin. A corn is thickened skin on the top or side of a toe, usually from shoes that do not fit properly. A callus is thickened skin on your hands or the soles of your feet.
The thickening of the skin is a protective reaction. For example, farmers and rowers get callused hands that prevent them from getting painful blisters. People with bunions often develop a callus over the bunion because it rubs against the shoe.
Neither corns nor calluses are serious conditions.
I've been finding some short but helpful videos about rock climbing. This guy says it helps if you climb with someone who climbs at or above your level and the Dynamic Duo definitely fit the bill in the above category, I might add.