What Recording and Mixing Levels preferred?

I've heard various things about optimum recording levels for Sonar, but would like to know what others aim for. One person in this forum shoots for peaks at close to 0 to track, then mixes down to -10.

My guitar teacher, who thinks he's the ****, says to track at -12 for headroom. Whatdya think? Anybody use limiters to set their tracking peaks?

Bill