Here’s a nice video from Aquatech featuring Phil Gallagher talking you through how to shoot with a wet port and a dry port.
The wet port technique is pretty standard and the same one I use, although I keep up the spit routine much more frequently than every 5 minutes as suggested in the video, I find the more often you spit the better the technique works.
The dry port technique uses candle wax applied before the session which is then buffed off, I prefer using natural oils from behind your ears as I explain in my Water housing users guide part 3, but it does the same thing.