I'm a seller, and I already knew a terrific agent that I had worked with before. I got rid of half my furniture, boxed up all the clutter (having watched HGTV), and then went to see him because I *thought* I was ready. I wasn't..
He came over to see the house, so that he could get realistic comps for me. After he saw what he was dealing with, he told me that the wallpaper (ALL over the house) would not be popular among buyers here and he suggested that all of it should go. While he said he was no good "at this decorating stuff", he also said he had heard that painting in neutral earth tones seemed to help. He also noticed some repairs that needed to be done and said the house should be in perfect repair. And finally I already knew I had to recarpet the whole house, since the carpet was wildly colored and not neutral, stained, and over ten years old. He said that my curb appeal was great already so I didn't work on that so much.
It took me a couple of months and over $9K to have workers get rid of all the wallpaper, paint in neutral earth tones, get a new neutral carpet throughout, and get all the repairs done and have a handyman search for other repairs (like kitchen draws that stick, and doors that are hard to shut, a ceiling fan that wasn't actually working, and a million other little things that I hadn't noticed because I was used to them) and fix them. The house looks 100% better and it is a joy to live in. Who knew? LOL I should have done this years ago. Anyway I'm glad I did it before listing because the competition here for buyer interest is fierce. After the work was done my realtor came back, took a look, and got some new, realistic comps for me and the next day we listed the house.
It may or may not be advisable to do all of this in your location with your particular housing market. But my point is, your realtor knows what sells and you need to line up a realtor that you want to use, get him over to your house, and listen to any suggestions he may have.