Sandie...

If you're just starting out PayPal will probably be your best bet. It's easy to deal with, people are familiar with it and trust it. The costs might be a little bit higher and that's only a might because you don't know yet what your account will look like. It's all based on volume with number of invoices, average dollars per invoice etc. factored into the equation.

Track your credit card costs monthly and then after a year or so begin shopping your processing around for a better rate. Starting out as you are, most would quote you their highest rate...a year from now, that might be a much different story.
Good luck
Denny