I use a lighter to leak-test my propane meter, too
Use 2-3 wraps of teflon tape on each threaded connection. When wrapping the teflon, wrap it in the same direction that the fitting will thread on - that way when you screw on the fitting, it doesn't take off the teflon.
I've occasionally had a brass fitting that won't hold 120psi (max a propane tank will put out, in my experience) no matter how much teflon you use. In that case, I just put a teeny bit of clear epoxy or superglue on the bottom of the threads, and screw it in. It'll never come back out, but it won't leak either....
Leak testing the entire thing in a bath tub before installing it on the gun is probably a good idea.
Peace,
Pete Zaria.