Don't look to profit from sorrow.
All Buddhist practice, and mind training in particular, is about ending suffering. Anticipation of gain from others' suffering, or even complacency about it, breaches the intention of this practice.
Train in taking and sending alternately
Use reminders in everything you do
The five forces while living
Don't talk about others' shortcomings
Don't dwell on others' problems
Give up any hope for results
Keep these two
Train without preference
Don't get things wrong