A spare Canon BP-511 Battery Pack is an essential item in the
Canon EOS 10D,
Canon EOS 300D Digital Rebel or
Canon EOS D60 kit.
The Canon BP-511 Battery Pack is a Lithium-Ion battery -
as maintenance-free as the current crop of digital camera batteries get.
The manual simply tells you to use them and charge them as you desire.
My personal recommendation is to have at least two Canon BP-511 Battery Packs.
Keep one in the camera,
keep the other(s) fully charged in your bag - ready for immediate use.
Giving each battery a complete discharge/charge cycle during each use cannot be bad.