I usually try to get 2,000 words a day. However, this NaNo has been a catastrophe for me, so I'm currently going for 4,000 a day, until I catch back up.
As for motivation, staying active on NaNoWriMo forums helps me stay motivated. Other people talking about how well they are doing keeps me going, because I'm competitive and if others can win, I can too.
On that same train of thought, I also enjoy word wars. The competitive nature of the war, and just sitting down to write for 10 or 15 minutes straight, as quickly as I can, helps me reach daily word goals.