One of our top tips on getting the most out of your paint sample tester pot is to, instead of painting it directly onto the wall, try painting it directly onto a piece of paper. As the light changes so much in our homes throughout the day, painting your sample onto paper will allow you to see the different tones you're going to have when it's night-time and when it's daytime.
Another advantage of using a piece of paper is it allows you to move the colour around the room, providing a clearer sense of how the colour will look and resulting in you not having lots of paint patches to later paint over.