The first step in developing a healthy relationship is figuring out specifically what you want. When you are in between dating and single would be the best time to do this. Make a list of all the things that you want in a partner. Some attributes may include dependability, sense of humor, positive attitude, and responsibility. The more clearly you can envision the qualities of your future partner, the more clearly you will be able to weed out all of the ones you don't want.
Next, learn from your past. Look at your previous relationships and compare them to your list of qualities that you want. Do they measure up? What was the attraction and seriously examined what happened to the relationship and yourself. Don't settle for less than what is on your list. Apply this to your life and use it. Being in a relationship just to be in a relationship is a waste of time and energy and can be detrimental to your well-being. Be assertive and take control of your life.
Remember that the biggest factor in maintaining a relationship is commitment to each and the relationship. If you are in a seriously unhealthy relationship seek professional help. Both parties in the relationship require the same amount of energy and care for it to work. If it becomes unbalanced, it will likely lead to one person becoming resentful and bitter towards the other. The other person may not be ready for what you are looking for and needs more personal development time. In that case, enjoy dating.