Plants are exciting, aren't they? :)
One thing I wish I had done from the get-go is to keep a 'plant diary' with pics or drawings of the plants, their common and scientific names, what works for them and not, how big they get, etc etc... Also, to make a tank sketch naming what plant is where.
Really -- do this. It'll help you keep track, and over time you'll find it helps you learn more about aquatic plants. Plus, it's fun!