There is a big difference in picking up a snake and holding it and handling.
Anyone with no or very little experience can get lucky and hold a snake that won't bite no matter what you do to it.
But handling properly is an art that takes into account a lot more then just feeling the weight of the animal. Its sort of like a good horseperson who is at one with the horse, its the same handling a snake, you learn to read the snake and make adjustments that not only control the animal but help it feel comfortable too. One of my biggest pythons, a large female bredli who I don't handle much, can be a real handful even just getting her out for a clean, but with gentle hooking and then gentle handling she is ok for a while before she starts trying to grab with her coils as the fear of being handled gets too much for her. I don't push past this point, as she starts getting grabby and stiffening up the next step is definatly a bite so I put her back in. Whether more handling will calm her down or not I am unsure, I don't have time to put into it and considering that snakes hate being around people anyways I won't bother her with it.
So learn to read your animal and learn its body posture. Things like is it moving or has it stopped, is it in a position that it can strike from, I have never been bitten by a wild python and catch dozens each year. Give all snakes respect and show patience when handling or about to pick up. The more you handle them the better you become.