Lots of brushing. You gotta train hair to do what you want. When it gets longer it will, hopefully, behave and lay down better. Ideally you should have been brushing it the whole time.
I use something like this. With the little rubbery thingies on the end. It detangles real good. I condition my beard every other shower, brush, brush, brush, sometimes I'll blow dry, low on cool, and brush while I dry.
You don't wanna do too much with it, don't over wash or get too much crap it it, just brush, you got natural oils you don't wanna strip out.
Also if this is your 1st or 2nd beard it just might not grow in great. I always tell people if you plan on growing a beard don't shave a thing for 2 months, no shaping, trimming, nothing. Then you got a nice even base to start on.