Rescuers were called out more than 1,800 times in England and Wales last year - the fourth year figures have increased, according to Mountain Rescue England and Wales.
In Wales, mountain rescue teams dealt with 422 - 23% - of those incidents.
A campaign has now been launched to promote greater safety awareness.
A checklist compiled by Ordnance Survey and Mountain Rescue England and Wales helps walkers to prepare for their trek.
It emphasises the need to plan ahead, check weather conditions, wear the right kit and carry paper maps as well as GPS devices.
John Grisdale, vice chair of Llanberis Mountain Rescue, said people needed to take responsibility for their own safety.
His team covers Wales' tallest mountain, Snowdon, which attracts about 450,000 visitors a year, and last year volunteers were called out nearly 200 times, putting pressure on their family lives.
"Usually it's a lack of preparation leading to us being called out or having poor footwear," said Mr Grisdale.
"They often get themselves into difficult situations because of a lack of planning in advance.
"Snowdon is perhaps prone to the day visitor who comes thinking that there are easy paths towards the summit. There's a cafe at the summit, there's a railway... these are unique features and [people think] it can't be a difficult mountain to get to the summit.
"Unfortunately all mountains inevitably have some sort of danger."
In April, Central Beacons Mountain Rescue - which covers the Brecon Beacons - said 2016 was the busiest year in its 54-year history,
Walkers are being urged to be better prepared before heading to the hills, with mountain rescue teams feeling the pressure of increased rescues.