The best advise is: Know yourself, Love yourself, and Trust yourself.
You have to know what traits you want, need, or desire in a mate (before) you choose a mate. After all you are responsible for your own happiness.
Answer the following questions; Do we share the same values?, Do we want the same things for the relationship? Do we naturally agree on how to obtain those things? Is there a (mutual) depth of love and desire for one another? For people who feel they have met their "soul-mate" the answers to each of these questions is an easy yes.
Having said that there are other factors to consider such as one's age and station in life. If we are talking about two 15 year olds on the verge of breaking up that is a whole lot different from couples in their late 20s and beyond. Youth is about exploring and learning about yourself and what you want out of life. When we're young we really haven't figured out who we are!
Truth be told most of us fail our way to success when it comes to relationships. Therefore it's unrealistic for the most part to believe any relationships we have in our youth are going to lead to "happily ever after." There is a lot of personal growth and evolution that takes place in our youth.
For those of us who are older we have to figure out (why) we want to breakup. Knowing why helps to avoid choosing the same type of person in the future. Every failed relationship should teach us lessons about ourselves. Did your mate commit a "deal breaker" in your eyes? Have they "changed" or did you "change" since the start of the relationship? Are there traits you wanted in a mate which they do not have but you thought you could live without? Have you reached the conclusion that you can't see yourself spending the "rest of your life" with them and therefore it would be a waste of both of your time to keep letting days, weeks, months, and years float by, Have you fallen (out of love) or desire to be with someone else?, Do you no longer feel loved by your mate?
"There is no amount of work or communication that can overcome being with someone who does not want what you want."
"Never love anyone who treats you like you're ordinary." - Oscar Wilde
"If you are unhappy in a relationship and (choose) to stay then (you) are choosing to be unhappy."
Awhile back I wrote a hub called A Breakup Method. https://hubpages.com/relationships/ABreakupMethod...