'Enjoy life, enjoy being a man' is probably the best advice that you could give to a potential father.
A happy man/husband/father = a happy man, wife and child.
Happy-go-lucky Jack Nicholson type, or aloof and distant Clint Eastwood type, whatever floats your boat, whatever feels comfortable for you is best for you.
If you are happy and manly then your woman will be happy and womanly. She will be more likely to be in sound in her mind (fewer neuroses and bi-polar tendencies) and sound in her body (less flab/corpulence).
During the gestation (following the conception), if you are happy in yourself then your woman will be happy in herself and so she will produce more testosterone in her body because of the influence on her lifestyle which will influence the development of the child in the womb, and thus its future physiology and psychological disposition (see the articles on 2D-4D ratios and in-vitro testosterone exposure, which I think CH has mentioned several times in the past). A child exposed to more testosterone in-vitro is more contented, less neurotic, more outgoing, more sociable etc.
During the formative years of your child (0-5 years) if you are happy in yourself then your woman will be happy in herself and your child will be his self because of the positive role models set by his father and mother as individuals, and by the positive relationship that they have with each other and other people. Good role models are better than bad ones: an unhappy and weak father means a tyrannical/domineering mother, and consequently a weak undeveloped son, and/or a bitchy demanding daughter (who always sees her mother getting her way by nagging said husband). Man is an imitative creature after all. If the son and daughter see only weak men and domineering women, then that's what they'll likely grow up to be like.
During the next ten to fifteen years of the child’s life if you are happy in yourself then your woman will be happy in herself and your child will be happy in his self. Your child will continue to imitate your positive manly traits (inquisitiveness, decisiveness, optimism etc) and will take them in his own direction. And then, when he finds a suitable woman, he will be able to pass on those positive traits to his own wife and children, thus perpetuating the process of enjoying manliness.
It's a brilliantly simple concept really: A happy man/husband/father = a happy man, wife and child. Unfortunately that concept seems to have been lost or corrupted somewhere along the way.
The best advice to give any father or prospective father is to enjoy being themselves, enjoy being a man; the rest (the happiness of the wife by means of increased testosterone, the happiness of the family by means of positive role models, the happiness of the neighbourhood by means of sociable neighbours etc) is then just purely academic.