[Huskrrrr]

Rule #1 Stand up to a bully.

Worked for me.

[CrazyIvan]

Rule #2. Have a best friend that is 6'5” and 285lb. That worked out well for me.

[ZirconEncrustedTweezers]

Rule #2: Fight back if you have to.
Rule #3: Kick his ass if you can.

[driftless2]

My youngest brother was very slight and non-aggressive when he was about 11-12. Therefore, he was picked on by some bigger kids (bullies) at his school. I paid for karate lessons for him since his/my father didn't want to do anything about the situation.

Shortly later, my parents moved to a different state, and my brother went to a new school. The first week of school, the "toughest kid" in his class started picking on him. My brother punched him in the face, and the "toughest kid" ran home crying. Later my brother became good friends with the same kid. Strange result, but nobody picked on my brother again.