Uh oh... Should I give away the secret? Shhhhhh.....
The secret is: The Law of Total Tricks.
In a competitive auction, add your trump length to partner's known trump length. Then bid to the level of your fit. If you have an 8-card fit, stay at the two-level. With a 9-card fit, bid to the 3-level. Add a level for a useful void. Deduct a level if you have a weak doubleton in opps suit or your hand is flat. Ignore points.
Don't tell anyone