There’s no formula, but here are some significant (albeit arbitrary) approaches to working with text on poster:

Modernist – spare, ordered, small, separate from poster image, asymmetric, lots of space

Jackie Casey

Hamish Muir

Josef Muller-Brockmann

Eclectic – energetic, noisy, varied weights, sizes, position, intuitive

Paula Scher

Illustrative

Heads of State (and others, like the Small Stakes and Spike Press)

Experimental/conceptual

Lana Cara posters

David Carson, Raygun Magazine, 1994

Neville Brody, and here

Emigre