How much should you charge to trim someone's bushes?

You may give them a flat rate to trim the bushes or charge them by the hour what ever works out for the two of you, I do not think it is fair to give you a set price I do not know if you have ever even trimmed a tree or plant or bush, and then you have to clean the mess up that you make also do you have the tools to do the entire job or will they be supplied. How many bushes are their what size are the bushes do you think it will take an hour or days.

one large bush .. he told be to pay whatever I thought it was worth. I need a guideline.

If you need to ask this question you should not be allowed near a bush.