Hello,
I am about to try and hang my first doors and have learned from various
places, this group included, that it's more difficult than it looks. Can't
say I'm surprised. Apparently a critical item is getting the jambs
perfectly spaced, plumb and square, again no big surprise. One suggestion
I've read involved cutting a 1x2 brace of the final door width + 1.5in
(2xwidth of jamb stock) + say 1/8in for the hinge side gap and tacking that
flush to the outside edges of the jamb assembly while shimming to ensure
that the desired opening is maintained.

What also comes to mind (though I haven't read this anywhere) is to cut 2
braces of say 10" in length and tacking these so as to brace the top corners
in a 6/8/10 triangle thus ensuring the tops of the jamb assembly are square.
Yes these would have to be mitered so no material overhung into the shim
space but that's pretty simple to do. Anyone care to comment on this?
Seems to me if you can get this braced assembly centered in the opening and
shimmed plumb on both sides you are good to go.

Eagerly awaiting responses telling me how wrong I am. (actually that's
true.. cause that's when I learn things)

ml