OK, I don't know much about electrical, but I'm trying to finish my basement and this is what I have so far. I have a 50 amp break in the main box feeding a subpanel in the basement which has two 20 amp breakers. One feeding about 8 outlets and 1 feeding another 8 outlets. I'm using 12/2 wire for this so far. My question is this the proper setup so far? Also, I'm about to start on the lighting and planned on putting all the lights on one breaker? Would this be OK and would I still use 12/2 wire? Thanks

Wire size is tied to breaker size. If you have a 20 amp circuit you stay with 12/2 wire. It is not only Ok it is a MUST. If your dropped to 14/2 you'd have wire that is rated for 15 amps but on a 20 amp breaker, no protection there. The number of outlets on a breaker is not much of a concern but the things plugged into those outlet is a concern. What else will be plugged into the same circuit as the lights? If any of these things trips the breaker you'll be in the dark.

It all depends on what you will be plugging into the outlets. If you put a space heater@1500 watts and a toaster oven @1500 watts and then a TV. You will be overloaded on any 8 circuit run. Make sure to spread the load around. I would put the lights on at least 2 breakers. That way you are not in total darkness if the breaker trips. Many electricians will run 12 AWG to a junction box using a 15 Amp breaker and then run 14AWG for lights. Unless you are going to really load the lighting, 14 AWG if fine. How many spaces in the subpanel and who installed it? Subpanels are treated differently when it comes to the neutral. It is isolated from the subpanel and wired back to the main panel.

Lets keep in mind you can not mix 12/2 and 14/2 wire on a 20 amp circuit. OP states he has two 20 amp breakers so no 14/2 anuwhere is allowed. http://www.cerrowire.com/default.aspx?id=46

Gentle reminder, if you are in an area that has adopted the 2008 NEC codes, that you will need to use tamper proof receptacles and Arc Fault breakers for a new installation.

I suggested a 12AWG with a 15 amp breaker, not a 20, for a home run, then go to 14. I would hope he is adding new circuits for the lighting.

I am just trying to stick with what he has in place and what his actual question was. He already has two 20 amp breakers and circuits in place. I would like to see lights and outlets on separate circiuts but he should not think he can bring in 14 gauge wire or cable into this setup.