Popping is the easiest way whether you deal with a baby o an adult however sometimes older snakes are harder to pop as they have a better control of their muscle.

I pop at any age very rarely probe

In both cases the best way to learn is to have someone near you show you how to.

Do not attempt probing on your own if you have no experience you could seriously injure your snake.

Learn to pop with someone as well it's the best way to know the right placement of your fingers and how much pressure to apply.

Try finding a local herper near you or even a member here local to you and willing to teach you how to do it.