The one stumbling block for people is how to get the pit or stone out of the centre. Recently I was typing up a recipe for use in one of my cooking classes that called for a sliced avocado. As an afterthought I included a tips section on how to remove the pit as that is the one question most people ask me when we are dealing with this bumpy bulb. It's easy and once you get the hang of it I'm sure you'll find that you'll include it's creamy flesh in more and more dishes.
To pit an avocado, run a sharp knife around the entire length of the avocado reaching the pit with each incision. Twist the two avocado halves in opposite direction and pull apart. Take a sharp chef knife and gently rap the blade into the pit. Twist the knife while gently pulling on it. Using a cloth for protection grab the pit and pull from knife and discard.
To keep the halves whole, simply take a soup spoon and place the side of the spoon between the skin and flesh. Move the spoon completely around the avocado and scoop out the half.
To dice an avocado in the skin, take a paring knife and slice through the flesh down to but not through the skin length wise. Repeat about 1/2 inch apart 3 times. Then repeat this cut but horizontally. Then using the same method as removing the halves, simple scoop out the flesh and the avocado should come out in diced pieces.
To slice an avocado, either scoop out a half as per above and place the half flat side down on a cutting board and slice or use the dice method but only make length wise cuts and scoop out.