The same types of basic precautions used in any public area should be taken when using a public laundromat. These include being aware of your surroundings and always keeping an eye on your belongings.
Avoid leaving clothes or other personal items unattended at the laundromat; as this gives potential thieves an easy opportunity. For an extra set of eyes and added security, bring a friend along if possible. Try to wash clothes during the day or at busy times when more people will be present. If you feel uncomfortable or witness suspicious activity, leave the area immediately and call law enforcement.