At first, it is important that you like your mate. Therefore a first impression through a personal meeting or a phone call can be helpful. Additionally you can use google-search or you can look for common friends in facebook to get more information about that person.
The same diurnal rhythm is also an advantage. If you are used to go to bed early you won’t get along with a person who party all night long and in contrary. That’s why it is important to clear these things previously.