As a homeowner, you will want to make whatever changes are necessary to enhance the enjoyment of the home for you and your family, but be aware that the cost of the improvement will often not be totally recaptured in an appraisal or sale of your home.
Typically, neutral decorating (new carpet, paint, wallpaper, etc.) is money well spent. Larger improvements, such as additions and four-season porches, must be considered on a case-by-case basis. Be sure to take a look at your neighborhood when planning changes and try to keep improvements in line with other properties in the area.