i have re-done my car with larger AN 12 stuff, and made up any number of connections, so i have some experience with leaks.
First, carefully determine if your leak is where the braided hose is inserted into the end fitting, or is the leak at the mating 37 degree flare, or at the NPT fitting on the
oil filter adaptor, for instance. This can take awhile. You do use sealant or Teflon take but only on the NPT fitting threads, not anywere on the AN fitting.
It is helpful to use hose and fittings from the same manufacturer. There is a difference between "nipple" and cutter designs. Don't overtighten AN fittings, you snug them down so the mating faces contact, anything more will strip the threads.
I have also found that i can re-use an AN fitting on a hose end about one time, before it is stripped. I have also once cross threaded one AN fitting on a hose end. Inspect the 37 degree mating surface for any tiny defect, if i drop a male one, i have bent the aluminum male end a tiny bit, and it would not fit without leaking. When making up the AN hoses, you have to mark the hose to be sure when you screw the end fitting into the hose connector, you are not pushing the hose out. I use an AN fitting vise block to properly hold the fitting, so i don't bugger up the finish, you can get them from race places for about $25 or so.
I have had oozes at all of the potential sites, and tracking each one down has sometimes been frustrating, and cost me more money for more fittings. I personally like the Russel ones, and the Aeroquip ones the best. By the way, when i am done with a length of hose, i flush it with hot soapy water, then trickle a tiny bit of gas thru it to rinse out any metallic particles in the hose and the connection.
I cut my hoses with a 32 tooth new blade, they last only about one or two hose cuts, i use motor
oil as a lube, and of course tape the hose properly before i cut it.
It is not hard work to make up fittings, and the support brackests, but you have to be meticulous and very precise and patient.
In the end, i have had several connections i just had to toss and make over again, for no reason i could tell. Maybe somefittings are just defective, too.
If you want any specific advice, let me know.