Can you share tips on doing diaper change to prevent messiness because child spits out milk, shoots out poo poo and urinates during diaper change especially for baby boys.

You just have to be super fast in changing. At the same time slowly educate your LO that he cannot pass urine while you are changing diapers for him. After some time, he should get it. If not, you can always put a wet tissue over his private area while you clean his bum. At least if he urines, it won't shoot in your face.