This answer to this question is really no different than tips to consider when hiring a plumber or dentist.
You should ask whether the attorney has experience in family law and, in particular, the county in which you are seeking to revise parenting time. You could call the Bar Association, but they will simply give you a list of names. Don't base your decision on advertising. There is no correlation between a large advertisement and an effective attorney. Make phone calls. Often, attorneys will be willing to speak to you on the phone without charge. You can use this time to discuss the case in general terms and get a feel for the attorney. You need to have a good level of comfort with the attorney, including the ability to communicate. If you are not comfortable, it will be hard to work together. Discuss fees up front. Most attorneys ask for an up front retainer which is applied to the fee. The fee itself is based on an hourly rate. The hourly rates in your area can range from $150 to $300. The amount of the hourly rate has just as much to do with the attorney's overhead as it does his or her experience.