Ok, here's my recipe.
Izzy's World Famous Guacamole
4 avocados, puréed
1 medium tomato, chopped
1/2 white onion, chopped
Salt to taste
Mix ingredients in a bowl. Add salt to taste. Serve immediately. Enjoy

Easy peasy, and a crowd pleaser too (I have photos of people licking the bowl clean)
Most places mentioned above will add other ingredients such as olive oil, pepper, lemon juice, etc etc etc but IMO is innecessary and it only ruins the taste of the avocados. A small amount of lime juice is ok to keep it from going dark, but don't add too much.
BTW the avocado is ready when you push the stem and it gives in slightly but it doesn't squash. The skin should be very dark green or brown and even in color.