Go and look up trees and their properties. Find the trees indigenous to your area. Then take a limb or from an adult tree. Do not sacrifice the young for your desire. Or go to the lumber yard and find the wood type you would like to use.
If you get the limb from a live tree, ask permission first and then leave something behind (a quartz crystal, water and some tree fertilizer) to give back to the tree and thank it for its sacrifice to you. Then let your limb cure for a good while 6 months or more so that the wood is dry before you start crafting the wand.
Google "trees for wands" and also look up the Celtic Tree Song that start "Apple for the Lady, Oak for the Lord, Roan for protection, Holly for the sword..."
This is a primer on trees and their best uses.