Be friends first. Make sure you take time to talk over and discover what each other's values really are by observing how your intended lives their life as opposed to what they say. Interestingly enough, my husband first came across my radar when he was being a white knight in shining armor to another woman.
Make sure you find a man who has a healthy relationship with his mother. (This can mean different things depending on the situation.)
Take your time. This is an area where "fools rush in" really fits. Life will eventually provide us with difficult circumstances and troubled times. See how they hold up when bad things happen. Some say our basic nature comes through at those times. Granted, I took maybe too much time but under the circumstances, (we lived in different towns for a good deal of our courtship), it made sense.
In the end it all paid off. We were a couple for 9 1/2 wonderful years and finally tied the knot. We have been very happily married for almost 4 years. My husband is kind, considerate, hard working, smart, funny, generous, thoughtful, and has a good moral code. Every day I endeavor to treat him with the love, respect, kindness and consideration that he deserves.
Oh, and take a LONG road trip together. (Yes, really!) It's a great way to assess compatibility when you are in a car with someone for hours at a time. If you find you are constantly getting on each others' nerves for one reason or another and can't stand being with each other in a car, it may be like that when you are married. Re-think it!