How to ensure pkgsrc groff is preferred over groff in base

[Gerard Lally <lists+netbsd.users%netmail.ie@localhost>]

Thanks to all who contributed to the recent groff thread. I now
understand the pros and cons a bit better.

I posted the following question here, to netbsd-users, instead of
pkgsrc-users because it is connected to that thread.

What is the correct way to ensure pkgsrc binaries and libraries are
used instead of their equivalents in base? For example, after installing
pkgsrc groff I now have groff, grn, grodvi, grog and more in both
/usr/bin and /usr/pkg/bin. Do I create multiple aliases, or just change
$PATH so that /usr/pkg/bin is before /usr/bin? For user, and/or root?
Would changing $PATH create other problems elsewhere?

I realise this is basic UNIX stuff I should understand better; it's
just that I would like to know the standard or correct way of doing it.

--
Gerard Lally