Your book of spells is a very important tool as you learn more about witchcraft, and though not everyone keeps one in the same way, you should have some kind of spell journal to keep track of information and the spells you've learned.
Sometimes referred to as a Book of Shadows, this is your personal book of rituals not some specific historical book. No matter what you want to call your book of spells, you really should have one.
It doesn't have to be some fancy, leather-bound journal filled with careful hand-inked calligraphy. Even just a binder filled with website printouts would make a very handy reference guide.
The thing is, your book of spells should have more than just spells in it. If you want to learn more about what works for you and what doesn't, you should also keep a running journal about when you cast each spell (if you have) and how well it worked out. Did you make any adjustment? When did you perform the spell? What kind of results did you notice? After how long?
This kind of information can be more valuable than the spells themselves. If you realize that your love spells all do better when cast after dark, and that they typically take 7 days to kick in, you can be more tuned-in with your next spells.
You can keep a lot of other magickal info in your book of spells too, if you really want to build a helpful resource. The uses for herbs, crystals, colors and numbers can all be very handy details to have when you start to write up your own spells.
Another thing about your book of spells is that it should be personal, and not passed around for just anyone to read. Of course, you can share it with whoever you like but try to keep it personal in order for it to hold onto its power for you. Don't freak out if someone gets a peek at it, just keep it private for the most part, especially from people who wouldn't understand its meaning.
So don't go casting spells willy-nilly. Get a book and start keeping track of what you're doing. A nice little book blessing spell might be a good place to start to make your book more special before you begin.