I would suggest to also make an investment of buying a book called National Audubon Society Field Guide to North American Trees. I believe they also sell them for different regions. I love mine as you are able to take the book with you out to the field and look at the bark, leaves, blooms, etc...
Some trees were hard for me to identify 100% due to the maturity of the tree. The bark on a 5 to 10 year old tree is sometimes quite different in color and texture when compared to the same tree of 50 to 100 years old. You might have to wait one full revolution in seasons to more accurately identify as the book I mentioned shows key leaf parts, flower blooms of the trees, fruit and cones, tree bark, and even some trees leaf color in the fall. Its an excellent book in my opinion and a good investment for the do-it-yourselfer.
Good luck