Number 1: Be ready for thin air
"All of these peaks are high-altitude," Athearn says. "So everyone, and especially someone coming from a lower altitude, needs to be prepared for the lack of oxygen and the physiological problems that can come from being at high altitude. They need to make sure they're physically in shape to handle the many hours they'll be on the mountain."
If they're not, climbers should improve their condition and stamina by tackling less demanding terrain and work their way up to the point where they can take on a fourteener without worrying about faltering halfway through.
Athearn points out that "weather and lightning-related hazards occur regularly. Most people are out on the fourteeners in July and August, which coincides with the monsoon season, when there are almost daily intense thunderstorms. So people should get an early start to maximize the likelihood that they'll be climbing in good weather and won't be subject to the general afternoon thunderstorms."
Number 3: Even an early start may not be early enough
The caveat to tip two above is that "the weather gods don't have watches," Athearn concedes. "So lightning and thunder can come at any time of the day. A lot of people buy into the notion that, 'If I'm off the mountain by noon, I'll be okay.' But there can be lightning at 9 a.m., 10 a.m. Most storms come in the afternoon, but there's no guarantee they won't pop up. So when I'm on the mountains, I have my head on a swivel, looking to see if clouds are building or getting really dark. If they are, it's time to go down, no matter what time it says on my watch."
Even if the weather is warm in town, it can be cold enough to produce snow at the top of a fourteener, even at this time of year. That's why checking snow conditions is a must. The online resources for doing so include the National Weather Service's Colorado fourteeners page.
"With snow conditions, you need to approach it with the mindset of, 'The mountain's going to be there tomorrow,'" Athearn points out. "If anything doesn't seem right, back off."
Number 5: What looks firm may not be
"There are a lot of different hazards that can be faced on fourteener routes," Athearn allows. "Some of them have very easy trails and pose little in the way of what we would call objective hazards — things like rock falls. But there are other scrambles that are quite committing, where people are subject to handholds breaking loose, rocks falling from above and, depending on the season, avalanche cornices breaking off and falling on people."
Testing handholds in advance rather than simply assuming they'll hold firm is a good idea, as is visually examining the route to identify the places where rock falls are most likely to occur.