In no particular order.

Keep your knife wicked sharp. Sharp knives are safer because you are less likely to try to force the blade through wood and end up slipping when it breaks through.

Get a Flexcut knife or something similar. Their metal is harder and will stay sharp longer.

Alternatively, get an X-acto type hobby knife. The only two blades you'll really use are the ones in the preceding link and the #22 blades. Get the thicker handled X-acto knife. It's more comfortable and holds larger blades.

Buy some basswood blanks. Basswood is hard and has a tight grain which makes it yield more accurate cuts. You can get it pretty cheaply at Michael's or other craft stores.

Start with something geometrical or inanimate. Trying to carve a person or animal right off the bat is too hard. First, they have too many details. Second, people know what they are supposed to look like and can compare yours to reality.

A really cool starting project is two linked rings from one piece of wood. It's really not that hard. It just takes a fair bit of time. When you are done, it will really impress your friends.

Buy some band-aids. In fact, one set of Flexcut hand chisels I bought came with a little set of bandages in the box. :-0

Have fun with it. If you make anything cool, send me a PM or post it to r/diy.