Being a better sub to me is being able to trust your dom/domme. If you know you're going to be taken care of, you are going to enjoy it more and things will come naturally.

If you don't trust what's going to happen, don't believe the dom/domme is doing it for the right reasons or is capable, then you tense up, resist, and generally behave badly.

It's a hard thing to give yourself up to another person. But it's also what makes BDSM relationships so much more powerful.

Good luck