Crediting is love. Please credit sarcasticons or sarcastic_lass in the keywords or comments of the images you take.
Not hotlinking! I have limited bandwidth, y'know?
I love comments by they are by no means necessary. Crediting is far more important to me-- because then other people can find me if for some reason they want to use my icons, too!
Go ahead and use my icons as bases or customize/edit them as you see fit. I really don't care as long as you credit the base image to me.