I see from the collecting sticky that you have probably read the article that was linked. If you have not checked back, the broken link has been fixed. My apologies.
Here is another excellent series that goes into detail on how Walter Pall collects trees.
Perhaps you can post a picture of the tree in question. Most enthusiasts who collect trees look for above average material but a young tree might be a good exercise for you. You will need to have your potting medium on hand before you dig the tree so begin to research bonsai soils now.
You will also need some nursery pots of various sizes. Use the smallest pot that will comfortably accommodate the tree. Of course you will not know exactly how large that will be until you dig it.
Read the articles and don't forget the sticky about bonsai soil.