you can just add some malted wheat to your specialty grains. or i guess you could add some wheat malt extract to the mix. excellent cleaning and sanitation always helps w/ good head retention and a nice collar of foam. a good cold water rinse of the beer glass prior to pouring up helps too.
If you have not been using steeping grains, try them as well. They not only impart flavor and color, I have heard that they also infuse proteins that help the head hold up.