Caring for and Wearing a Beard
A summary of beard-care advice.
If I had to sum it down to one thing, wash your beard. Seriously, wash your beard. Not too often, maybe only 2-3 times/week, but wash your beard. Condition, too. If you have dandruff, try a dandruff shampoo. If it persists and dries out your beard, moisturize the skin with conditioner or another moisturizer and resume regular shampoo application. One of these two options will cure your dandruff.
For those interested in the long-form specifics, I just use whatever non-dandruff shampoo that tickles my fancy, comb it through my beard, and rinse thoroughly. Then I apply conditioner and I make sure to comb it throughout the beard and especially on the skin under my beard. I'll wait 5-10 minutes (sometimes I just get out of the shower at this time) then return to gently rinse. I don't agitate my beard by drying it but I brush it straight down and after the shower so it stays in a vertical orientation. Then I spend the rest of the day not touching my beard and then my face because that just spreads oil from your beard to your pores which is dumb.
Oh, and comb your beard if it's long enough for it. Polite society will thank you (or at least they should).
This is my most successful and presentable routine for maintaining a beard that goes down to my chest. Any questions, feel free to ask.