Assess his personality. Is he shy? He will appreciate some boldness on your part to take away the pressure of possible rejection. Is he overtly aggressive? If so, what is underneath that behavior? Possibly insecurity covered by that facade? Is he arrogant and full of himself? Pass! Men are not that hard to figure out. A great new book to understanding men and how to push their buttons is on amazon kindle edition called "Practical FLR" by JM Scott. It is a fun read.