1. Most (but not absolutely all) female threads are parallel. It's generally much easier to make a tapered male thread than a tapered female one.
2. I've never found it necessary to use jointing compound as well as PTFE.
3. Clean both female and male threads, then fit together without any tape, compound or whatever. If the fit is quite tight, start with 12 wraps of PTFE and try. Should require a spanner and a bit of heft to get the tail in without reaching the end of the threads. If the fit is looser, start at 15 wraps. If very loose, start at 20. If you can't achieve a tight fit, remove, strip off all the PTFE, wrap with 5 more than previous attempt and try again. 4. There are other options:
4.1 Loctite 55 sealing cord. Pretty much the same principle as PTFE but gently rough up the male threads first and wrap as directed on the packet. That is some along the threads, some across.
4.2 Pipe sealing compound (Flomasta or Loctite). Very good, but requires both male and female threads to be completely clean, and particularly free of grease. Apply a bead right round the 2nd and 3rd threads of the male thread, screw in. Wait a minute of two for it to go solid. Fit to be used after about 30 minutes.
