This is my experience and there's science to it. What we perceive as "punch", even if two people might disagree on relative punchiness, is a spectral envelope. Simplistically, the set of volume levels over time for all of the harmonic overtones of the note. So there's a harmonic factor, and an envelope factor. Where you pluck up and down the string influences the harmonic content, because you're putting energy into the string at a specific point, and the relationship of that point to the center of the vibrating section of string affects which partials are emphasized. How your fingertip interacts mechanically with the string is the other. It theory, the string is either struck or plucked - in one case, the sound envelope comes from the string accelerating into higher tension, in the other, accelerating into lower tension. Aggressive bass guitar playing isn't just plucking anymore, and the way the fingertip strikes and releases is what will control the attack envelopes in subtle but real ways.
Short form: Work out your method by deliberately varying *where* and *how* you pluck the string until it sounds right.