The most important thing you can do is to clean them without being too invasive. This means hardly ever using any form of liquid cleaner except in rare cases when it is specifically designed fluid for cleaning digital video tapes. If you do use a cleaning solution it is important that you use very little and follow instructions carefully.
Your best practice should be to get a micro fiber brush and go into both the bottom tape revealing area as well as the center circles where the spokes are located. Go through this area lightly, and if you can get a micro fiber cloth in there that will be great as well. You can try using cloth that is specifically used to clean glasses. This will help prevent scratches.