The first aid kits need to fairly comprehensive, the items need to be rotated occasionally, and, of course, you should know how to use all of the items in the kit.
- Put together kits that meet your specific needs (examples here, here, here)
- Take some first aid courses (examples here, here, and here)
- Be sure to stock any necessary prescription meds
- Consider stocking additional items that would be useful (like tissue, Pedialite, etc)
- Keep some first aid books on hand (examples here, here, and here)