Never underestimate anyone no matter how small, incapable and out of shape they may look. That can also to applied to seniors. You really don't know everyone's past history or experience. Or what mayhem they might be capable of. A lot of crazy people/street fighters out there.
Don't be a head hunter, aiming to hit the jaw or side of the face first is not always the best attack. The head is a relative small target to hit, can easily be missed or blocked.
Try striking with the heel of the hand rather than a closed fist. Generate much more power, even from a short distance close up.
Imagine there is straight line down from the neck to the goin. That can be a elect target area. Including the solar plexus, the junction for an important nerve center of the body and bladder, prime targets. (caution, either a blow to the solar plexus or bladder could kill)
Learn ground fighting.
BB'ers greatly depend of ego and image, but looks are often deceiving when it come to the will and the ability to fight: either street, bar, road rage, etc..If having no serious past experience in fighting, than don't. But you can learn. 500+ benches have little value when it comes to serious fighting. Potential of being beaten by a experienced street fighter who pushes up 135lb benches max....pretty high.
Actually street, bar, etc fights do not last very long. Never had a timing on any, but probably 30 seconds. Unless a guy will dance around and really does not want to really fight...than that maybe 60 seconds. Main cause for fights seem to be women, who can actually encourage a man to fight...stupid, you bet.