Easily removable caps
Have you ever had a cap on a tube of paint so glued on that you needed pliers to remove it, sometimes ripping the tube in the process? When you first get new tube colors no matter what kind of paint really, take a tiny dab of Vaseline and coat the threads of the tube. Take a paper towel to help coat the threads and wipe off any excess. Take care not to get Vaseline inside the tube. Now replace the cap. This will make removing the cap in the future much easier. This process may have to be repeated in the future if you can tell that the cap is starting to stick.