Light is so important when taking a photo. I try to use natural light, when I can. When you’re taking photos inside make use of any window light that you have, but make sure the sun isn’t directly shining through the window as that can cause a rather harsh light. Then notice the direction of the light falling onto the subject, is it behind, in front or coming from the side. I mainly like the light coming at my subject slightly from the side so it creates a mixture of light and shadows, but it’s fun to try if from different angles as it can change a scene dramatically. Have a play around and find out which you prefer.
Sometimes when it’s quite dull outside, then extra lighting is needed. You could use a torch, phone light or lamp, but don’t point it directly into the persons face. You can have it coming from slightly to the side of you or you could try bouncing the light, which means angling the light source at a white or light neutral surface, like a ceiling or wall, so that the light bounces off the surface and creates a much softer light.
There are many different ways to use light, some ways create a natural look and some more dramatic, you can have a play around and see which you prefer. Photography is creative and there is no one size fits all approach to how a photograph should look. It’s all about finding your style and what you are happy with.