There will be a lot of differing opinions and methods, but I will give you mine, based on what I have gleaned from having just remodeled my own house, and also spending the last 10 years in construction and commercial millwork industry, and hearing a lot of opinions.
Yes, I would definitely use glue.
In addition, I would invest in some Collins Miter Clamps
These are invaluable for any miter joints you may encounter.
Second, nailing may be required on some joints to maintain alignment, and I think most would aim to keep those nails on the top side of the header piece of casing, primarily to minimize visibility.
But, I would next recommend investing in a biscuit joiner, and biscuit every miter joint. This will insure proper face alignment, as well as add more glue surface creating a much stronger joint, that won't require any extra nailing in most cases.
In addition, biscuits work in very think casing materials.
Beyond that, a lot of very good installers like to use the Collins Edge Pocket Jig but this really only works on thicker casings, and is more if you are looking for bomb proof casing assemblies.