I'm a mother of two children and have several nieces and nephews, so I've changed more than my fair share of diapers. I have a son and daughter so both of my diaper changing experiences were quite different! I think it's much easier to change little girls than it is little boys.
I think the most important trick to changing a diaper is to be as quick as possible. The quicker you are means that baby has less time to get cranky, irritated and squirmy! Keep everything necessary for diaper changing in one spot for easy access! That includes diapers, wipes, ointment, lotion and powder.
It's also important to make diaper changes fun! That's right, FUN! Play games, sing songs, laugh and talk to them the entire time. I also kept a few "special" toys at the changing table that were only used at diaper changing time! This keeps their focus and attention on you and not what's going on around them.
Make sure you're always alert! Little hands are quick and they can grab onto the power, lotion or even the dirty diaper in a matter of seconds which can quickly turn to disaster! They can also roll over quickly and fall, so never take your eyes off of them, not even for a second!
My children are now 11 and 8 years old and have been out of diapers for years now. Last time my 18 month old nephew was here visiting, I jumped at every chance I could get to change his diapers. It brought back that little bit of "baby memory" that I've been missing for quite some time now.
In the end, you have to make sure to enjoy every aspect of your children growing up, including changing their diapers. Before you know it they will be grown, moved out and having children of their own. Cherish the memories no matter what they are!