Generally I don't think people should charge for their services until they can do the designs perfectly. There are several options for you.
do them for donations. Price your patterns from say $5-20 and see what people think of your work.
OR you can just say we are learning and will give you 1/2 price .
YOu can charge an hourly fee-$35 .oo per hour untill you get lighting fast and can do perfect henna under pressure.
When you get your speed up to the other great henna artists in your area you can start to increase your hourly fees.
I know there are some wonderful artists in the Pacific Northwest.
Justine, Hilary, Karen, Tiffany, Wendy, are just a couple I know personally and can recommend.
THere are many more and they are a great supportive group.
www.magicalmehndi.com
take a look and see if you are ready for big jump into the business of henna
best of luck in your new endeavors
Flavia