Question about legal California Growing

Ok, so I've never grown before but I live in San Francisco and was thinking about growing a few plants for personal use. Before I start growing I will be prescribed a med card which, as is my current understanding, permits the following under prop 215:
12 plants total, six of which can be mature.

Now let's say I have a few friends who have med cards, is there anything special that we would need to do to achieve the status of a non-profit collective/cooperative?

I'd really like to start growing and will keep things as low profile as possible, but I also really don't feel like going to prison so I want to see what people with more experience think is reasonable.

Thanks in advance!

then I'd suggest just growing for personal use for you and your buddies who all have med cards and you can all grow. lol. but its legal at a state level but the federal government still deems it illegal so the feds could bust you, not the cali state troopers or whatever.