1. -  More of a beefy candle, less wick more body, more volume (preferably).

2. -  Aggressive opposing candle that occurs after the orderblock.

3. -  Coupled with a displacement/FVG after the move from the orderblock.

Here you can see a clear example of an ideal bearish OB, price leaves behind a small displacement, after an already good impulsive reaction to the downside, comes back and fills it up to continue the run towards SSL.