The most important thing that you must consider is to know your need. This means, you will need to know whether you need financial ad visor for your business, your personal finance, do you need them to advice them on your insurance, etc.
The following article will be a great reference to you. http://financialplan.about.com/od/personalfinance/a/choosingaplan.htm
So far as their fees are concerned, they are very much dependent on the type, nature and amount of work you seek from them and it typically varies from 30 USD Per hour to 175 USD per hour.
I hope this helps...