K.B.
Well congrats on pursuing such a great goal that you seem so passionate about!
I don't know if I can be much help, but how much research have you done on this problem. I know you said many don't have helmets. Is it cause they can't afford them or they aren't educated on proper bike safety, or both? My guess would probably be both. There are certain things I've been told that make starting non-profits successful
1. Clearly identify what the problem is and what the cause of the problem is (you can't fix the problem without knowing what's contributing to it in the first place). If you have any friends who are like me and are great researchers/question askers/sociologist type people get them to help you!
2. Start small and work your way to being bigger. Your really excited right now, which is great! But, you might want to bring your thoughts back down to a smaller level and then work on expanding. Maybe start with doing one education/helmet give away event in your school district. See what kind of interest there is, what kind of advertising it takes, get an idea of how much things will cost, make a budget for one event. A lot of times when you do things like this, you can find local bike stores or even some larger companies that are willing to donate a certain amount of helmets or gear and possibly provide an "expert" to come and talk to people. Also, this will help you learn how to approach your audience correctly. Really to me, it would seem parents need to have the information on how to keep their kids safe, why it's important, etc. and kids would need to have it be more fun, interactive, and concrete for them. It seems like you are a big picture person (I could be wrong), but I know I'm a detail person (I rarely see a big picture unless someone presents it to me, then I can nail away at all the details they never thought of) so if I'm right in this assumption, find a friend/family member who is a detail person and see if they will go to work with you.
3. Measure your success. This will be important if/when you start trying to get grant money and donations on a larger scale. They want to see that not only is giving them the helmet successful, but that the overall program that goes along with giving them the helmet is actually causing an increase in helmet wearing. You can do this by maybe having a pre, post, and follow-up questionnaire for a sample portion of the families you interact with.
4. Get a really good accountant who knows about non-profit accounting. I took one class on it. It is very complicated with all the different ways to record and keep track of donations and funding. You have to make sure money is spent correctly and money for one thing isn't spent on something else. A good accountant is worth it.
5. Get a good lawyer. They can help you to set up the 501(c)3 status. They can do this way before you become big and huge. I have a friend who did it simply with a mission statement and an idea.
6. Get other agencies on your side! No non-profit is successful without the assistance and support of the other support agencies around them. They can be helpful with finding a "client" base, collecting possible donations, etc. You could do like an "event" of some kind at a women's shelter. They can request new helmets be donated or utilize a connection to get some, you bring in the educational aspects and a new partnership is formed!
Finally, be passionate and don't quit! It's a lot of work setting up ANY new business (which is what this is). Personally, I think these are even harder because your asking for a LOT of outside help when your first starting via donations and funding. But, if this is what you want to do, it should fall into place eventually. Just don't jump to far in getting started!
*I will note on here for your that I haven't started a non-profit, but I did develop and implement a successful case management program at my current job as well as develop all the standard operating procedures for my current position. Neither of these came from an idea I had. They actually were other people's ideas (and I give them full credit for having it), but I'm a detail person and I can hammer things out as soon as you tell me your overall concept. That's why I say, find your detail person and make them your best friend! I make my best friends big picture people for this exact reason!