S.J.
Hi J., to address your questions specifically ;
1- Professional Organizers do many things, and have different specialties.
The important thing to know is that they work with YOU to help you
achieve your goals, and address any specific challenges you might have.
You can go to www.napodfw.com to see a list of Organizers in your
area, and thier experience and specialities.
2-Your needs and your budget often determine how to go about it. If your entire home needs organizing but your budget can not cover your entire home, you can either focus on one room - or you can do a low-level sweep of the entire home- focusing on quick and easy decisions to be made in each room to make each room less overwhelming for you moving forward. This all depends on knowing your own "habits" that got you there, your biggest challenges you face, and your own goals. All of these factors are generally discussed at an initial consultation. At the end of the consultation there is an understanding and agreement of how you both feel is the best way to approach your home, and how you will best be able to move forward AFTER the organizer has left.
3- Yes, you can hire an organizer for just one area/room of a home.
4- Pricing varies, and is usually by the hour, but some organizers quote by the project. Organizers come in many levels of experience, expertise and specialities. Someone who is a new organizer, or does the work on the side, or just enjoys organizing- you can find in the <$25 range. Other Organizers have Professional Affliations with NAPO (national association of professional organizers) or have obtained certifications as an Organizer or Speciality Area such as Seniors, Hoarders, Relocation etc, participate in on-going training and education, and have substantial experience and resources are going to be in the $40-$75 range, or higher.
I hope that helps answer some of your questions. If you have other questions, I would be happy to answer them. I am a Professional Organizer and you can find me at www.organizedbysandy.com, or message me on Mamapedia :). You can also go to my blog and get some free tips that may get you inspired or find an article that addresses a challenge you may have. www.simplyorganizedbysandy.blogspot.com
-S.