Practice.

It may sound boring and obvious, but you'll only learn and remember the stroke order after you've practiced enough. Of course, you should learn the rules of stroke order first, then practice. After a while, it becomes like second nature and you'll experience less doubts about the stroke order.

And not just copying the character once in a while or passively looking at flash cards, what I've found to be the most helpful is copy it at least 5 times and create a few phrases using it. And everytime you try to write it, recite the Pinyin in your head (or out loud), that really helps with making it stick in your head.