@anon87969570 gave some wonderful advice! I second the idea about looking around and seeing what you have around you 
Sometimes- just like with Tarot cards, crystals, or other witchy tools- you’ll just feel that something is right 
If you do feel a pull to do research, here’s a list of Sacred Trees and some of their meanings/importance in Celtic traditions. Some trees have medicinal properties too, and I think it’s safe to say that every tree has magickal properties- but these may vary from tradition to tradition.
Good luck and blessed crafting! 