To me, Mastering is the most critical process in creating music. Especially Techno. Normally i wait till the next day after completing a track to start mastering. And i'm always taking breaks. Usually every 15-20 minutes, i'll stop for a bit. Check e-mail. Chat online, whatever. Then i start up again. I've been getting tips lately from someone in Cali who does mastering for a living. I'm very into this process and want to be able to do outstanding jobs. For me, the chain usually goes:

EQ>Compression>Limiting and maybe some VERY subtle reverb to add some depth and fullness.

With the L2, i find that moving the Threshold slider down untill you get some small movement of green in the LED section, then setting your output db to whatever you want (i usually set it at -1db) will yield good results. This should get you right at the 0db level w/o going into clipping. I think the hardest part of this for me though is compression. I'm not versed enough in this area. Sometimes i feel i may over compress sometimes. Compression is important to me as i like my tracks to have nice punch to them.