Lots of practice, use your thumb to hit the edge of the coin to give you more control, aim for a specific spot so you use the same amount of force and control t

Lots of practice, use your thumb to hit the edge of the coin to give you more control, aim for a specific spot so you use the same amount of force and control the amount of times it flips. You can also use a surface that absorbs more so the coin is less likely to flip after hitting it.