The quesiton is, are you making a long beard or a short beard? For short beards (mustaches, goatees) you can paint it on the texture and use a strong bumpmap. For longer beards you want to go with either a model or a morph/texture combo. What model are you using? Michaels come with beard morphs - the dork has some kicking around on the net. I tend to go with the model option - as you can do stuff with transparancy to make them look better.