1) Before you start painting, apply two coats to a piece of A4 lining paper. Hang the paper on different walls throughout the day to see how the colour changes in sunlight and under artificial light. You’ll find that the effects of light particularly influence whites.
2) Which direction does your room face? It’s important to keep in mind that most colours will look slightly darker and colder in north-facing rooms because the light is cooler and flatter.
3) Wet paint looks very different to dry paint. Try not to make any decisions until the paint is completely dry.
4) Most importantly, trust your instincts. If you love it, it’s right.