Baby's first holds head up (2-6 weeks)
Place baby's tummy on the floor to encourage lifting of the head and help to develop a strong neck and back muscle to roll and crawl later. After a while, baby can hold his/her heads for longer periods.
Baby's first rolls over (4-8 months)
Rolling over is from tummy to back and vice-versa.
Here are the video from tummy to back:
Warning: Always observe baby when he/she can roll over to his/her tummy as to avoid SIDS when he/she put her face on the floor and subsequently sleep.
Then the next milestone is to encourage baby to sit up unsupported. Place pillow around baby as to avoid any minor injury when baby falls to the side when baby gets tired.
Baby's first crawl (6-10 months)
Crawling requires baby to be able to hold his/her heads and soon use the hand and leg to propel him/her forward. Place a cute/colourful in front of baby to encourage crawling.
Baby's first walk (11-18 months)
Finally, the baby starts to progress to walking stage...
Here is a very good video in explaining the journey to walking