This isn't a full list - plenty of other dangers aren't covered here. Do a training course, read instruction books and accident reports, and talk to experienced climbers.
Bolt plates and wire-gate or ultra-light carabiners
Never use a wire-gate carabiner to clip a bolt plate. The gates are so thin that the bolt plate can come off the bolt even though the carabiner is still clipped through it.
Lots of WA routes have hangerless bolts, so keep wire-gates on the rope end of the quickdraw only. You save just 15 grams per carabiner, so 13 draws means 200 extra grams - less than a cup of water. Not worth risking your health over.
For the same reason, don't use ultra-lightweight carabiners on a bolt plate. Some sections can be thin enough to cause the same problem as a wire gate. Use a normal straight-gate biner. It doesn't need to be extra chunky, just not too thin.
Helmets
Consider wearing a helmet, especially at crags with loose rock up top like Churchman's Brook and the Perth quarries, where dislodged rocks land at the bottom regularly.
A helmet matters just as much for the belayer as for the leader, and it's far less annoying to wear while belaying. So why not?
Headlamp
Always carry a lightweight LED headlamp with fresh batteries on big cliffs. Otherwise, coming down off Peak Charles in pitch black darkness gets incredibly exciting.
Bolt plates and hangers
RP hangers won't fit some bolts, so it's best not to use them. Their hole is a touch smaller than other hangers, and they may not fit a "fat carrot" - a bolt hit so hard by the installer's hammer that its diameter grew.
Use PFH 90-degree hangers. They fit pretty much anything.
Anchor the belayer to the ground
If the belayer is much lighter than the leader, anchor the belayer to the ground with a sling or the slack end of the lead rope. Tree trunks, roots, bushes and rock features all work.
It doesn't need to be bombproof - you just need something to counter around 50kg of upward pull. There have been plenty of minor accidents where the belayer got yanked up into the overhang above them and came away with a very sore head.
Lightweight wind or rain jacket
If you're climbing a high, exposed cliff - Bluff Knoll, Peak Head South Face, Peak Charles - pack a compact lightweight wind or rain jacket and stuff it into a small camera case.
Jacket and case together should weigh no more than 400 grams. Clip the case to your harness with a carabiner, and check there's no dodgy Velcro that can come undone. It may not sound like a safety item, but hypothermia makes it easy to make bad calls and have bad accidents.
Discard old gear
World-famous climber Todd Skinner died when his worn-out harness broke. The legend is that the next week, everyone in Lander, Wyoming went out and bought a new harness.
Other gear breaks too. Ropes break, especially when loaded over sharp edges. Nylon ages and loses strength. Wires on nuts corrode and snap. Keep your gear in good shape and don't get attached to relics.
Knot in the end of the abseil rope
Unless you're certain the abseil rope reaches the ground, tie a knot in the end of it - a figure 8 will do. Many people around the world have died after abseiling off the end of a rope, often in the dark, and often when their judgement was already impaired by cold or exhaustion.
The best safety gear is training.
Nothing on this page replaces a course with a qualified instructor, or a day out with climbers who have been doing it for years. See what's coming up.