For distant stars it is even harder. We can watch the motion of the stars across the plane of the sky. Some move faster than others. Same speeds different distances. You know this one already.
Color is related to temperature via the Blackbody Law.
In the early 1900's astronomers found that stars could be classified via the strength of different absorption lines in the spectra. Some stars had many Hydrogen Lines, some had none. Some stars had many lines from calcium, some had none. Astronomers grouped the stars according to their spectral line strengths O, B, A, F, G, K, M O, B, A, F, G, K, M This is the spectral classification O stars are blue and hot. M stars are red and cold.