My advice is to get a good beard trimmer, but I don't know it would work on a long beard. Generally mine is short enough that I don't need to worry about anything other than keeping some of the wilder hairs in it from making it look ratty.
I have the same beard I had when I got married .. wanna say thirty, but no! ... forty somethin’ years ago! Trim it with scissors, shave my cheeks and neck. Trim my own hair, too. Saves money, and sometimes it looks pretty good.