Mangoes aren't cheap. At least not usually. And so when we do indulge and bring one home it's good to know how to cut into it to maximize the yield. So... here's the procedure.
Give the mango a good rinse and make sure your hands are clean. Take a paring knife and remove all the skin, working from top to bottom in strips. Try not to go to deeply while doing this.
Once the fruit is peeled take your paring knife, again, and starting at the top (which is the narrower end) insert your blade along the width of the fruit. The mango bears a flat seed in its center and the idea is to start the knife at the top and allow the blade to follow the flat side and contour of the pit. When one side is done repeat that step on the second side.
That leaves you two oval and somewhat flat pieces. Then take your paring knife and again, starting at the top slice the two remaining side ends and allowing the blade to flow the contour of the seed, slice off the rounded strip. So now you have two large ovals and two narrower strips.
Lay the ovals on a cutting board or plate, flat side down and from there you can cut them into strips as wide or as thin as you like and if you need them diced cut them again, crosswise, into squares. Use as needed.