I think you should ask around (and/or ask your Mom do this) what babysitters are paid in your area. Then charge just a little bit less to make yourself marketable. You would probably need First Aid training before CPR training if you are babysitting children.
If you were younger, $5 per hour would be perfect, but because you are older and experienced, I would say 7 or 8 dollars an hour. This is good for one or two kids, but any extra money depends on the individual situation.