Start with light. Most colorful bromeliads perform best in bright filtered light or bright indirect light. Too little light often means greener leaves and slower growth, while harsh unfiltered sun can scorch sensitive foliage.
Watering depends on the bromeliad. Tank-forming types such as many Neoregelias hold water in their central cup, but the water should be refreshed rather than allowed to become stagnant. The root zone should stay airy, never swampy.
Airflow matters. High humidity without airflow can create problems, so protected highland or greenhouse conditions should still feel fresh rather than sealed.
The easiest way to improve bromeliad color is usually not fertilizer—it is getting the light, airflow and basic watering rhythm right first.