Possible torn meniscus. how should i be using more caution?

May not be possible: Two things tear menisci 1) sudden violent loaded twisting can tear a healthy menicsus- don't fall! seriously- unless you are going to avoid skiing, sports, wet grass these aren't something you plan. If you have a torn acl, the knee moves more so fixing that may decrease your risk (controversial). 2) later in life the meniscus can wears out like a hose washer and come apart. Are less repairable.

Decrease activity: Avoid squatting and twisting activities.

No twisting.: Avoid twisting/pivoting on that leg. Usually walking is ok.