I've only attempted this once, and it was a complete disaster. Can anyone provide some tips for a beginner? 
I haven't tried this before but I found this youtube video that shows you how. Cut into the mango, starting where the stem was and going around the long way, just in to the pit. Reach in with a spoon and scoop around the pit, separating one half of the mango from the pit. Then scoop the pit out of the other side. 