First, slip the climbing shoes on your feet. The shoes should be snug on your feet and toes, but not tight. I rarely wear socks in my shoes so the fit is tighter and I can feel the rock better, but you may want to wear socks and decide later what feels right for you. If your gym doesn’t rent shoes, then bring a pair of snug running shoes, which will work fine on the easier climbs.
Next, pull the harness on by first stepping into the leg loops and then pulling it up so the waist loop is above your hips. These harnesses, especially designed for climbing, transfer the forces of a fall onto your pelvis rather than on your waist. Again, the harness should fit snugly on your body. Make final fit adjustments by tightening the adjustable leg loops as well as the riser on the back of the harness.
The most important thing to do after putting on your harness is to properly tie the waist strap through the buckle. For most harnesses, you pass the strap through the buckle and then double it back through a second time. If done this way, the harness will not come undone but if you don’t pass the strap through the second time, the possibility exists that the waist strap can come undone after a fall. Lastly make sure the end of the strap extends at least two inches beyond the buckle when you’re finished. After putting on your harness, ask a gym employee to check your harness to make sure it’s fitted correctly and safely. Later, after climbing a few times and you’re comfortable putting on your harness, you can ask your climbing partner to double-check your harness.
Lastly, clip the belay device to one of the gear loops on the side of your harness and get ready to climb.