Any helpful hints for washing New 100% cotton shirts to preserve color

Wash in cold water inside out with vinegar in the fabric softener cup. Use a "free and clear" or low suds detergent. I would only put in dryer for a few minutes. I just air dry my cotton items and then iron. I still iron almost everything anyway, so for me no big deal to do that. If you have a steamer, that works too. Hope this helps!

agreed, inside out in cold water. Vinegar to preserve colour for first wash. I do not ever put them in the dryer but hang to dry.

How much vinegar?

Absolutely wash in cold water...without a harsh laundry detergent. Use something gentle and adf half a cup of vinegar. would be perfect! If you have a way to hang your shirts up so they don't get those little hanger hooks on the shoulder, then do that... Absolutely avoiding the dryer will help maintain the Integrity of your colors and your clothing.

Pour in table salt into the wash water, this will set the color. This is the way you set the color when dying also. Good luck.