You got grants? Many congratulations, that's basically free money if you meet the requirements.
You need to take ALL 12 units. That's usually about 4 classes. If you want, you can go to your scholarship office and ask them what the exact stipulations are. Here's an example for you on a potential loophole. I am required to sign up for 12 units. Once that's done, the scholarship money kicks in (I have a tuition waiver and a grant for doing well in high school). I can drop as many units as I want at that point, the same amount of money is going to be there. However, an additional requirement of my scholarship is "Must pass 24 units per year." That means the following semester I would have to make up any units that I dropped. Last year I did something like this, I dropped to 9 credits and took at least 15 units the following semester to make up for it.
Unlike lyssword's experience, I wouldn't receive any money unless I had at least 12 units. They wouldn't give me partial money for 9. It seems silly, since it's a flat tuition rate at my university after 9 units anyway, so 9 units costs the same as 12. This is why you should definitely consult an advisor at the financial aid office and find out exactly what you need to do. If you start working weekends you should still be able to hold your full-time job, although I wouldn't recommend it. Part-time is the way to go when you're in college. At 20-30 hours per week you should still have plenty of time for homework, unless you're one of those crazy black hole majors like architecture. I say black hole only because it sucks up all of your time.
It'll be easier if you just take the 12 units each semester. College probably won't be hard for your first year anyway.
