With everyones posts so far, I haven't seen the most important thing listed. PRIME. Yes, you need to use a primer to seal any new drywall. Otherwise, you're going to use three times the paint and it won't bond as well. First, make certain it's clean. Quickly wipe down those walls with a tack cloth or at least a damp rag/towel. Professional painters often keep a paintbrush in their pockets soley for the purpose of sweeping away any residual dust. Never use this brush for painting itself -- just for clean up. If you're able, have the paint store tint your primer to match the paint -- you'll wind up with better coverage. Don't try to get one of those "one coat is all you need rollers," unless you like the look of paint sags. With a smooth wall, you should never use more than a 3/8" nap roller. Personally, I like the look of a satin finished paint -- though builders like flat. Flat is cheaper, and it hides wall imperfections better (the builder can be sloppier and the client is less likely to notice). With the two of you, it should go pretty quickly. Paint the ceilings first. One of you will cut in with a 3" brush, and the other will follow with a 3/8" roller. Pour your paint into another container -- NEVER DIP YOUR BRUSH DIRECTLY INTO THE PAINT CAN. If you have contaminated your brush (dirt/dust, etc) and you dip it into your can you won't wind up with a nice finish. Cut in one wall at a time, and while the first person is cutting in, the other can again be rolling out the field. Usually, the one cutting in will be much slower than the person with the field, so they can pitch in and help for the first few feet before grabbing the roller. Do not wait so long as to have the cut in portion dry. If this happens, you will have what is called hat-banding. You will have edges where it looks like two coats instead of one and this a darker or noticible line will form. If it's warm and you are concerned about the possibiility of this, add some floetrol to the paint. It'll help you keep a wet edge. If you have run out of paint and need to get more, always paint an entire wall with the new batch. Even with computer mixing it's not perfect. If you paint an entire wall it won't be noticed as light hits each wall differently, and your brain will not process that it's a different shade...
Anything else, feel free to PM me!