Adding insulation to your house is always a good thing to do. From an energy efficiency perspective or a comfort perspective you can’t go wrong with additional insulation. Here are a few thoughts.
If you are insulation the attic or underneath the house, doing this yourself is somewhat practical. For walls you must hire a professional due to the complexity and specialized equipment required. For attic insulating you need to determine how much and what r-value you are going to put there, and also how easily accessed the different areas are.
A great site for getting information on r-values and many other pros and cons of this type of project, check out Central Virginia Insulation to get a lot of ideas on thicknesses and costs. As long as you can get to the areas you want to insulate easily and don’t mind working in hot or cold attics, this is not that hard. Insulation comes in rolls and you need to buy rolls that fit the space between the joists. It is usually 18 or 24 inches.
You can remove the old insulation or roll out the new over it. The insulation comes with paper edges that you fold out once it is rolled, and staple the paper to the joists. Be sure to have a stapler with plenty of staples.
For underneath the job can be more difficult. Crawl spaces tend to be terribly inhospitable and working under there cutting the insulation and getting it rolled out into the channels you want while keeping it from falling back down onto your face can be a challenge. Just like the attic, you need to staple it onto the floor joists. You might even consider putting a heavy plastic moisture barrier on the ground under the house before beginning the project. As bad as it is, it is worse when you are crawling around in the dirt.