Getting everything ready before you start (clean diaper, wipes or cotton with warm water, ointment if you'll use it) saves you from having to step away mid-change with the baby on the changing table.
Step by step
Wash your hands before you start. Lay the baby in a safe place and never turn your back while they're on the changing table. Open the dirty diaper and use the diaper itself for a first wipe. Always wipe from front to back — this is especially important for baby girls, to avoid carrying bacteria from the anal area to the urethra.
Let the skin dry well before putting on the clean diaper; trapped moisture is one of the main causes of diaper rash. If you're using a barrier ointment, apply a thin layer. Fasten the new diaper comfortably — you should be able to fit a finger between the diaper and the baby's tummy, without it being tight.
When the skin needs attention
Mild redness usually improves with more frequent changes and more time with the skin exposed to air. Rashes that don't improve within a few days, or that have blisters or sores or look infected, should be checked by the pediatrician.