Check what other girls who are offering the same services as you do are charging in your area and adjust accordingly.

You will often encounter guys that have the audacity to tell you what you "should" be charging. You will notice that (by huge coincidence) it is the exact amount they have in their pocket / have decided they wish to pay you.

If you have done your research properly, and are happy with the amount you are charging, then take no notice of these idiots. We all get these, and I'm sure you would continue to get them occasionally even if you charged ?10 an hour. It's just a reverse attempt at discount hunting xx

 As has been said have a look at what others in your area that offer similar services are offering, remember though this is just a guideline if you feel you are worth more then charge that.

If you are getting the work you need then obviously there are plenty who will pay your fee, if you don't get the work then maybe have a look at your advertising (are you advertising in the right sites for your area? Is your ad being seen?) only after you have checked all this should you contemplate lowering your rates.

Also take into account how long travel takes you, I could charge ?20 less but I don't drive and even my nearest town is 1hr bus ride away. So that can be at least a 2hr round trip for a 30 min appointment, so I charge that extra bit because of that.