Take a line of operation which offers alternative objectives. This puts your opponent on the horns of a dilemma. It introduces uncertainty regarding that which is to be guarded against. Organize and deploy your resources in ways that facilitate adaptation to either. Unless your opponent is much inferior, do not attack until he has been disorganized and demoralized.
Psychological warfare precedes physical warfare.
Similarly, physical warfare can be psychological in nature. If at first you don't succeed, give up. Your reinforcements will likely be matched by the enemy. Moreover, successfully repulsing you the first time will morally strengthen him for the second.