As long as men have been wearing shirts and ties, wives have been trying to scrub out those dirt rings that seem to settle around the collar. You may feel it's a battle you can't win, but don't give up. Ring around the collar comes from the sweat and grime that collects on your neck and then rubs off on your collar. If you prevent the sweat and grim collecting in the first place, you can say good-bye to that embarrassing ring.
Keep yourself as clean as possible. It's very important that you shower shortly before putting on your collared shirt. This is because the shower will clean off any dirt or grime sitting on your neck that could cause or contribute to ring around the collar. Even taking a shower before you go to bed the previous night isn't really sufficient because while you are asleep, oil and dirt can accumulate around your neck, so make sure to be as clean as possible prior to getting dressed.
Apply a stain repellent to your shirt collars. There are stain repellent products out there specifically for apparel, or you can even buy shirts that have been treated with stain repellent that will protect your shirt against dirt, soil and stains.
Dust your neck with talc powder or corn starch. This will help absorb your perspiration and prevent your collar from irritating your neck.
Avoid activities that cause excessive sweating. Any type of perspiration will have a significant effect on the cleanliness of your collar. Change into athletic clothes if you know that you'll be doing any type of strenuous activity. Sometimes it's tempting to carry out certain activities in your dress clothes and collared shirts to save time changing, but in order to completely prevent ring around the collar, you'll need to minimize the amount of sweat that your collar is subjected to.
Pre-treat the collar with a stain remover. Specialty stain fighting soaps and gels work to break up the beginning stages of collar stains much better than plain laundry detergent alone, and they are very simple to use.
Wash your shirts immediately after you are done wearing them. The longer that you allow them to sit after they have been worn, the easier it is for ring around the collar to set in. Even though it may seem troublesome to wash them right away, it will go a long way towards keeping your shirts looking their best and preventing a permanent stain from setting in.