Safety
Safety is the highest priority when climbing. The following list provides some guidelines.
You should know how to belay and you need to be familiar with the belay device you use (in particular read and understand manufacturer’s instructions) and you need to feel comfortable using it.
Make sure that the person you climb with knows how to belay with the belay device they are using (in particular read and understand manufacturer’s instructions) and they need to feel comfortable using it.
Be aware that thinner ropes tend to slide through belay devices more easily EVEN IF the belay device is supposed to assist in breaking the fall.
The partner check before attempting any route is absolutely crucial; climber: check the belay device is properly attached and used; belayer: check the climber is properly attached to the rope.
You should know about your gear: How old is it, can it still be used, was there a potential situation (among other things: dropping something, heavy fall, accidents where high friction is involved) that invalidates the integrity of your gear.
Note, that this is not meant to be an exhaustive list nor has the CERN Climbing Club any authority or responsibility in providing any standards. If you do not feel comfortable climbing or belaying, please consider taking appropriate courses!
Gear recalls
From time to time manufacturers recall certain gear for various reasons, in particular when safety features are compromised. One can check for instance the website of the UIAA for an overview. In addition, manufacturers usually post their recalls on the websites.