I would not agree that these are usage habits, or even unix specific. But they are nifty.
- Make directory trees in a single swipe.
- Change the path; do not move the archive.
- Combine your commands with control operators.
- Quote variables with caution.
- Use escape sequences to manage long input.
- Group your commands together in a list.
- Use xargs outside of find .
- Know when grep should do the counting — and when it should step aside.
- Match certain fields in output, not just lines.
- Stop piping cats.
http://www.ibm.com/developerworks/aix/library/au-badunixhabits.html?ca=lnxw01GoodUnixHabits