A world of fun is available in that dark and dingy space, but before you start creating the basement of your dreams, assess your wants and needs.

What to Consider Before You Begin

Space. Don't be afraid to dream big, but be realistic. "You want to make everything fit for what you want to do," says Scott Varn of Harmony Interiors. If your heart is set on a big multipurpose space with game tables and a home theater system, make sure there is ample room.

Moisture. Before you start any work on your basement, you should detect and fix water and humidity problems. If you get water in your basement or regularly use a sump pump to pump it out, address this before adding walls, floors and furnishings.

Mechanical Systems. You may have a furnace and a hot water tank on one wall and a water filtration or water softener system on the other. It can be tempting to move systems into a space separate from your finished basement, but don't unless you have to. That will involve rerouting plumbing, ductwork, wiring and possibly even a gas line. Plan to design around existing systems.

Decide How You Want to Use the Space

Unlike a typical upstairs remodel, where you have one room that is designed for a specific function, your basement renovation depends on how you want to use the space. The basement can be a multipurpose space, and design elements you choose for a media room will be different from what you want in a guest bedroom.

Remain flexible, as your plans can change. If you want to house a pool table, make sure you have enough space around the table for players to use pool sticks without hitting the walls. If you decide to build a home theater, plan to have a couple of feet between rows and enough room for seating.