pipe compound

FYI, so would I.
A lot less mess, and I trust it (just start it a thread or so back from the end of the fitting.)
I noticed where people mention that it deteriorates, but I have never had that problem with fuel parts and teflon.

Are any of what you are going to use flare fittings?
If so, there isn't much you can do with those except lightly snug then wiggle a little and snug a little and wiggle a little and tighten down.
It helps to mate the surfaces a bit on assembly if you have one that leaks at all.