I believe the grip and bridge needs to be a personal connection to the cue, like holding a fork, spoon, or knife, we all use a slightly different technique and grip pressure, but it serves the same purpose. I'd recommend experimenting with your grip and pressure to see what really works well for you, if you just "always held the cue lightly" you may be missing out, because many top professionals hold the cue firmly (many times they don't appear to be, like Shane and Dennis O)
When under pressure we tend to "tighten up", so I recommend holding the cue firmer in critical situations. I ask Earl Strickland what his grip pressure is like when he's playing his best and he said "Death Grip"......he was kidding, but you can tell there's nothing loose or dainty about Earl's top game!
There must also be a "groove" established in your bridge so you can feel the cue going absolutely straight. When you get to the point you KNOW your cue is delivered straight and pure through the cue ball you're ready to jump up some levels. I teach how to align your body on each shot to either a Center\Center or Center\Edge reference, this gives your subconscious mind the same beginning position every time and this is VERY important. (The secret is the feet position)
I"ve talked to several champions players about their grip pressure and what they strive for to get the most connection to the game.....what about you, have you tried various grips and grip pressures?