When you get new goggles, burn off the silicone on the inside of the lenses with a lighter. Then give the inside of the goggles a good scrub down with toothpaste and some baking soda. It really helps to defog them.
Don’t take your regulator out of your mouth when underwater. If you need to cough, spit, burp, vomit, etc. you can do everything INTO the regulator.
Refrain from foods before you dive that will give you gas or make you burp. It will make for a more pleasant dive and easier breathing! And this really should be a tip of its own, but don’t forget to stay well hydrated between dives.
Did you know there is such a thing as warm-water (silent) hypothermia? Make sure you are well protected even in warm tropical waters by wearing a 3mm wetsuit or shorty.
There are two types of divers: ones that pee in their suits and ones that lie about it. If you have to go, you have to go. Don’t be shy about weeing in your wetsuit. I conveniently left out the fact that I had about 12 pees (rather potent vitamin laden ones) during my open water dive training.
If you do end up ‘wetting’ your suit, regardless if it’s a rental or not, be sure to give it a good soak in antibacterial liquid wash or fear the wrath of disgusting residual urine stench!