In culinary school, the first rule a student learns is how to properly salt boiling water. First, boil the water (with a lid). Don't add the salt to the cold water! The reason for this is salt increases the boiling point of water, so it will take longer for it to come to a boil. That's minutes of your life you can't get back, folks! Once big fat boiling bubbles appear in the water, remove the lid and toss the salt in. How much salt exactly? Enough so that the water should taste like the ocean, but if you're not really interested in slurping a teaspoons of salty water to taste, here's the ratio to remember:
3/4 tablespoon salt to 1 litre water
As you can see from the photo, I usually use a little more, but I also like my pasta and boiled veg on the saltier side. Once the water is salted, it's ready for the pasta or vegetables you're looking to boil.