What's the best way to copyright the songs I write?

In a copyright application, the work you submit is the protected work. If you submit multiple songs, you are protected for the compilation.  There is tangible benefit to submit for each individual song. Similarly, you could submit lyrics/composition under TX form, as SR form will only protect that medium. Keep in mind, if I transcribe and sell the lyrics I hear in your sound recording, that would be infringement of the sound recording copyright.  The concern is, the more you pack into a filing, the easier it is for someone to copy a small percentage of the work and have the court find noninfringement or fair use because such a small percentage of the work was copied. You can go to copyright.gov and see how well known artists protect their work. There is nothing wrong with seeing what they do and copying their process.  Granted they have deep pockets, but copyright protection is sufficiently inexpensive that the fee should not be a barrier to sound protection (pun intended). Good luck, Todd