Assess the Mess
Before breaking out the cleaning supplies, take a good look at the basement to determine the cause of the mess and assess what needs to go. Ask yourself about its current use or examine how you might be able to use it in the future. With its planned use in mind, go through everything in the basement and sort it into piles. Separate piles for keeping, one for donations and one for items to toss out. Purge the basement of outgrown toys, items the family no longer uses or broken appliances.
Organize the Piles
Sort through the keep pile to get it organized. Gather, box and label all the holiday decorations together by seasonal event. Group the sports equipment together. Make piles of household supplies, canned goods and whatever else fills up your basement. Arrange shelving and storage bins to keep things organized, with items frequently accessed near the middle shelves and children's toys on the bottom in bins. Label boxes and bins so you know what's inside. Install a pegboard with hooks to hang sporting equipment or other items out of the way.
Start the Cleaning
Grab the cleaning supplies. Add a large fan to circulate some air in the space. Start at the top and work your way down. Wipe walls with a mild 1 part ammonia and 3 part water solution to disinfect and clean, and then rinse and dry. Sweep or vacuum every corner including under the stairs. If you have area rugs, don't just vacuum them, take them outside, shake them out and let them air out for an hour or two. If the laundry is in the basement, clean the outside of the machines and check and clean behind them and the dryer vent as well.
Clean Even Deeper
While organizing and cleaning the basement, it's also a good time to do any needed repairs and repaint anything that needs it. Check and clean furnace vents and filters. Look for any signs of moisture, mold or mildew. If present, remove mold and mildew with a solution of 3/4 cup of 5.25 percent household bleach and a gallon of hot water, allowing it to sit on the affected area for 10 to 15 minutes before rinsing. When cleaning mold, wear a safety-approved face mask to prevent breathing in the spores. Set up a fan to dry the area well. When finished, add basement cleaning to the weekly household duties.