What do you need to improve your communication skills so you have less conflict and more understanding in your relationships?

A higher esteem of myself. I so often do not say what I really feel or what I need and want because I am afraid that there is no room for that. If only I would find myself a person worth a while, I would be much more relaxed but also clear on how I want to be treated, what I think, what I feel. Right now I am too much pleasing the other person which often leads to misunderstanding that I am fine with all that, while this is not the case.