You have to truly know yourself, what you want and need in a mate. Then you must remain true to yourself as you begin dating or going through the selection process. The goal is to find a mate who "naturally agrees" with you on the major things in life and also shares the same relationship goals. It takes more time to get to know someone than most people are willing to invest before becoming a couple.
Quite a few people rely too much upon chemistry or simply "go with the flow" when they meet a new person rather than taking a hard look to see if they match their so called "requirements list". Before they know it they become "emotionally invested" and then the "hard work" begins. (Trying to change water into wine or finding a way to fit a square peg into a round hole) Basically they want to change the person into "The one" they had on their "list" to begin with! We're far better off wating to find someone who (already is) what we want.
Opposites may attract in the short run but it's (like that attracts like) in the long run. Couples who agree most of the time tend to have easy loving relationships.