1. Don't get into a relationship with an agenda.
People often stay in a relationship because of an agenda. An agenda is a belief that something needs to be a certain way for us to be "OK". For example: "I must be married by 30 yrs of age." When we have an agenda, it will often get in the way of the more beneficial decisions we would normally make.
2. Open your eyes and be willing to see red flags.
I cannot tell you the number of people who have told me that they never saw the unhealthy qualities in the marriage or relationship until way down the line. We are talking sometimes years. They often report that the behavior "just showed up one day, out of the blue." The truth is that the behavior was there all the time but was ignored. "Love is blind" is not a helpful mantra when it conceals warning signs.
3. Read up on some things you can expect in relationships.
Learn the concepts and skills that will help you navigate through a relationship - and life in general. For example: How do you have difficult conversations in a relationship? How do you determine healthy and unhealthy behaviors? Without knowledge of these skills and concepts it can feel like navigating in the dark, not knowing what you are bumping into.
4. Give him time to show his true qualities.
Watch out for consistent behaviors for at least 6 months. It is very difficult to hide your true qualities for more than 6 months without being a sociopath - and for sure, no longer than one year. And you would have to be a really skilled sociopath on top of that for those unhealthy qualities to remain "hidden".
Watch for consistent behavior in the relationship. This holds true for negative as well as positive behaviors. There may be an underlying reason for a person to temporarily exhibit negative qualities. We all make mistakes but there is a difference between occasional "mistakes" and an overall theme of repeated negative behavior. Conversely, occasional "good" behavior does not negate an overall theme of unhealthy behavior.