Answer : Good interior design begins with a purpose. A well-thought-out purpose defines the needs of the space and should guide decisions before furniture, paint colors, etc., are chosen.
An example is deciding what space will be used for cooking or eating. Will it be purely aesthetic? Purely functional? A place to socialize with guests? When you know your intended use(s), then you can decide on aspects like seating/table arrangements and lighting style and intensity to name just two of many possibilities. It also helps to pace yourself; it is much more efficient not to make all your choices at once, but rather finish one step at a time as you narrow in on the specifics or as components change over time.