I agree with Sue that you should obtain your certification first before marketing your services. Given that you will be new to coaching, perhaps you can invite friends and family to participate in your services once you get your certification. Then, you may feel more comfortable marketing yourself.
As for determining packages and structure, you may be able to get an idea of a fee structure from what others are charging in your area. The same would go for developing packages.
One thing I would recommend is to even make connections in your area with other health coaching professionals. You can even do informational interviews to gain more knowledge. I did this few years ago and it was very helpful as I started more health coaching.