On most threaded fittings, if the threads on both halves are good you want 3 wraps, or 3.5. Every once in a while you will come across a fitting where the female thread is slightly large, needing an extra wrap but in 1/2" I've never seen it happen. Use a wrench, but don't be too forceful, teflon tape has lubricating properties and you could damage the female part if over tightened. I suggest (I was a plumber for 20 years) if you have a leak, remove the old teflon tape, wrap new on 3.5 turns (when you buy the tape, buy good quality tape, not harbor frt stuff) then turn it in finger tight, then use a wrench and add 1 more turn.
To be honest, teflon tape should not be used on plastic fittings because of the ability for it to cause the female part to split, that being said, I often use it. A good teflon thread seal compound (paste) is better to use. The Rectorseal Tru Blu linked to above is good stuff, available at most plumbing supply houses (where the pros shop), maybe not at Lowes or Home Depot. Likely Amazon has it.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.