Climbing

The most obvious advise would be: find a mentor (somebody more experienced) to show you the ropes (pun intended).

Next best alternative is to do a course that teaches you the basics and then take it slow from there.

In terms of practising trad climbing, you can sometimes find bolted routes where you can still place your own gear. Climb these routes like you normally would but also place your own gear. Now you can take test-falls to see if your gear holds. If not, you will still have clipped the last bolt so you won’t just fall to the ground.

In terms of practising a route before committing to sending it on gear only, looks for routes where you can set up a top-rope anchor and practice it on top-rope first until you are either confident that you won’t fall or that your gear placements will hold.

Climb below your max grade, especially when you start. Placing your own gear and learning to be confident with it will take some time, don't stress it out with difficult climbs.

I like to talk with my partner about my gear placement right when he arrive at the anchor. So he can tell me how gear felt to him after I climbed (eg, if the red one popped out because I didn't place it well).

If you want a rest, tether yourself to the last gear rather than resting in the rope. It puts less effort on the gear.

Similarly, always lay down in your anchors so everything is tight. You don't want slack between you and the gear because the shock of a fall has higher chance to pop it out.

A tree alone is fine to use as an anchor if it's larger than your leg.

Always take a headlight.

Don't learn any of these the hard way ^^