Maximize the use? Hm, that's a bit broad of a question..."maximize" depends on a person's usage and needs. Anyway you may want to start here:

http://wiki.maemo.org/Maemo5_101
http://nokiaexperts.com/tips-shortcu...00-user-guide/
http://talk.maemo.org/showthread.php?t=44309

If you ask me, for a fresh unit I would:

- Install NITDroid and then Install the Bleeding-Edge wireless drivers (you'd end up having a Nokia N900 that can do multi-booting)
- Download apps (you might want to try out Swappolube)
- Put music and games, or productivity apps
- Set up email and IM (I use my phone to check my corporate email - MS Exchange as well as chat on IM via Microsoft Office Communicator)
- Customize the phone to your delight
- Overclock your phone to give it a boost of speed (I have not yet done this yet)