what can you put on dyed hair to keep from fading? (other than wearing a hat)?

Start by using a shampoo and conditioner that is sulfate free.

The best things to do to prevent color from fading is use a mild shampoo (similarly, using a harsher shampoo like head and shoulders, or plain bar soap, to fade color). There are several lines of shampoo and conditioner out there to help prevent color from fading, but if you are on a budget, using a baby shampoo (Like Johnson&Johnson No More Tears) along with a conditioner for your hair type (moisturizing if you have dry hair, volumizing for fine hair, etc) does the trick. I have had every hair color imaginable, and this method has always proven effective for me. Usually I have to re-dye my hair from root growth before I do for fading color.

(I use No More Tears shampoo, and Head and Shoulders Smooth and Silky conditioner)

I'm sure you know, but there are shampoos and conditioners to prevent your colour from fading. I normally use L'oreal Elvive colour protect. It'll fade eventually whatever you do, but I use this and normally the my roots get very bad before it fades anyway.

Hope I helped. :)

Nothing. It doesn't fade, it just grows out the original color.

It fades every time you shampoo it.

it'll fade eventually. You just need to dye it again..

it'll fade no matter what. try permanent dye instead of temporary