Supplies:
Avocado(s)
Paring knife ( steak knife or similar)
Bowl
Favorite recipe

Simple steps to preparing an Avocado to be used for a guacamole dip, in a salad, on a sandwich etc...

Picking the best "ripe avocado" is the most important part of the "preparing".
The avocado should "give" slightly when pressing it with you finger.

Compare it to pressing a finger on your chin / forehead or if you close your hand ( making a fist) press at base of your index finger/thumb - soft but not too soft.

If there is no"give" in the avocado it may not be ripe enough nor ready to be used (maybe tomorrow), Too soft then it might be over ripe and could possibly be dark inside not usable (for me anyway)

See this link on how cut an avocado. www.instructables.com/id/How_To_Cut_an_Avocado/

Step 1: Making the Cut!

After picking and cutting the avocado(s) in half remove seed ( save seed for planting).
Make cuts length wise then cross ways.
This cutting will make it easy to remove the avocado from the outer skin.

Step 2: Squeezing Time!

After Cutting each half into cubes, just simply give one half at a time a little squeeze over a bowl.
You'll be surprised at how easily all the avocado cubes fall out, with little or no mess.

Note: if you want long slices don't cut cross ways, but they will not squeeze out, you will be able to remove them with a knife.

Step 3: Final Step...

At this point the avocado is out of it's skin in the bowl and ready for your favorite recipe. If you plan to make guacamole dip simple mash/smash all the avocado cubes with a"fork."

Simple Recipe for Guacamole Dip: mashed/smashed avocado, chopped tomato, salt and pepper to taste, Sprinkle a little lemon or lime juice to help prevent discoloration (if you plan to eat it soon then it is not necessary to use juice) . Serve with tortilla chips, or spread on a sandwich.

Options: You can spice it up with hot sauce, chopped onions etc... endless

Planting the seeds, I have had very good luck growing avocado plants by simply throwing the seeds in the flower beds, I don't bury or fuss with them but they grow... they make pretty trees but mine have never produced.