A few weekends ago, I saw three separate recipes for guacamole on Food TV. Alton Brown had one, Michael Smith had another, and I think the Barefoot Contessa was the third (or Rachel Ray, who irritates me). All were nothing like my guacamole recipe, which is actually my roommate-from-grad-school's recipe.
Take one ripe avocado (do you know how many tries it took to spell that correctly?). You'll know it's ripe because the skin will be a dark, dull green. If it's shiny, or merely darkish green, let it sit on the counter for a day or two. Cut it in half and remove the pit - you can use the pit to try and grow an avocado plant, but it will take a long time and chances are, you live in a region that does not lend itself well to avocado cultivation. Anyways...
You don't need to peel the skin off. The skin is thick and stiff, and the innards are soft, so you can scoop them out (this bit only took me, what? Five years to figure out? Up until now, I've been trying to peel the buggers. All the while, scooping is so much easier. Duh.) Scoop the soft creamy insides into a food processor or blender - something that will make the mixture smooth.
Add about a tablespoon of lemon juice. You can use fresh lemons, but the stuff that comes in the fake plastic lemons is okay too. Blend a little. Add two tablespoons of mayonnaise, or whatever, to your taste.
You're going to have to add garlic, and it's up to you how much you want to use. I usually use one clove, but more is great, too. Chop it finely, and throw it in with the rest of the mixture. Blend briefly.
Now, these are the super-secret ingredients. You may be asking yourself why I am telling you if they're supposed to be super-secret. Well, I'm telling you so you can add them, but don't tell your guests what the secret ingredients are, 'kay? Alright - add a dash of Italian dressing and ketchup (catsup?). That's it.
Blend the whole thing until smooth. The versions I saw all kept them chunky; they used mashers as opposed to a food processor, so there were still chunks in the dip. But they weren't as smooth or creamy - it's just your preference, I guess.
If you leave the guacamole uncovered, or even covered, it will turn brownish (unless you've left it on the counter, then it will be fuzzy and green, which isn't good. Put it in the fridge when you're done with it.) It turns brown because avocados, like apples, get oxidized when exposed to air, which is why they turn brown. That's what the lemon juice does - delay oxidization, or minimize it. It's still good, and if kept in a covered container it can last a week or so.