If you've never worked with avocados before, you shouldn't be afraid to try them! Picking a good one can be a little tricky, but once you buy 2 or 3 of them, you should be an expert. I usually try to pick one with a darker skin color (as opposed to green). The firmness of the avocado is your best guess as to how good or ripe it is on the inside.
If it feels hard like an apple, it's not ripe yet. You could buy it if you don't plan on using it for a few days. To speed up the ripening process at home, put it in a paper bag and crumple the top of the bag to fold it closed. It should ripen in about a day. Check on it about every 12 hours or so and squeeze it gently to test ripeness. If you plan on using the avocado the day you buy it, you should find one that gives just a little when you hold it in your hand and apply gentle pressure with your thumb. Whatever you do, don't buy a real mushy one (one that gives easily and alot when you apply gentle pressure to it). It is over-ripe and you risk it being all black on the inside. And no one likes black guacamole.
2 ripe avocados
1/2 of a large tomato, diced
1/2 a medium onion, diced
fresh lime juice, to taste (1/2 to 1 lime)
salt, to taste
8 springs cilantro, rinsed and chopped
Slice the avocados lengthwise around the seed. Gently hit the blade of the knife on the seed and twist to remove the seed. Scoop the avocado out of the skin with a spoon. Depending on how soft the avocado is, use a fork or potato masher to mash the avocado. Add the tomato, onion, lime juice, salt, and cilantro and gently mix all the ingredients together.
Easy and delicious!