Probably the most effective strategy is hazing. Whenever you see them you shout, make noise, throw rocks and stones, etc. Anything you can do to enhance their natural wariness and fear of humans helps them and helps you.
Beyond that, keep potential food sources (garbage cans, etc.) out of easy access. As for warding them off up close and personal, pepper spray and maybe a stick or staff. A handgun would work, but you may or may not wish to carry one and in a heavily populated area the risks likely outweigh the benefits. Depending on where you are, coyotes vary considerably in size. Where we live, they rarely get much over 30 to 35 pounds and are still true coyotes. In other areas they are heavily intermixed with dogs and wolves. These things can get to 75 pounds and look like a german shepherd. The locals I would not hesitate to kick the crap out of if they tangled with my dogs. If I were dealing with big coydogs, I would probably depend on hazing and pepper spray if the area were too populated to safely "ventilate" the ones that did not get the message from hazing attempts.