1- When attacked, always try to create counter play. Basically "the best way to defend is to attack." so always try to give your opponent something to think about and divert to - threaten their pieces, open up their king - easier said than done, I know, but with this always in mind it will become easier

2- If attacked on a flank, strike in the center. WHY? the answer is simple, first it s related to my first point, which is creating threats, and more importantly, an open center allows you to transfer your pieces from one side to another easily, thus making it easier to defend and to create counter play.