Most of my work is server side (vim!), but on a client I just install firefox-esr with pkg_add. If there's a security update that I think I need, I'll 'make package' on the -stable branch in ports, and install that package wherever I need it. The -current branch keeps up to date with firefox pretty well if you want all the new features, but -current tends to move faster than I'm willing to keep up with.