Getting familiar with how the color wheel works and use the HSL color system. A good color scheme is basicically just regular offsets in hue angles, saturation, or saturation.
You can do things as vary hue by a few degrees, vary the saturation or lightness by fixed amounts, use opposite hues on the color wheel, etc. Some useful tricks to have if you are doing color grading as well. There are all sorts of known useful ways to combine colors.
The key insight here is that what is pleasing has some heuristics behind them. It's simple math once you figure that out. For color blind people, color contrast works differently for certain hues.
You can do things as vary hue by a few degrees, vary the saturation or lightness by fixed amounts, use opposite hues on the color wheel, etc. Some useful tricks to have if you are doing color grading as well. There are all sorts of known useful ways to combine colors.
The key insight here is that what is pleasing has some heuristics behind them. It's simple math once you figure that out. For color blind people, color contrast works differently for certain hues.