These next two tips are so basic that they might wrinkle your brain. Unless you're going for the more dramatic, hard-light look when you're shooting indoors (I'm usually not), a reflector and a diffuser are your new best friends.
For those of you who have no idea what a diffuser is, it is anything that softens light. Most of the time they come in the form of translucent white fabrics. Imagine you have a window that the sun is shining directly into leaving you with a hard, stark light. Putting a diffuser over that window turns that hard light into soft, even, glowing light. For the look that I love, this is perfect! I’m all about soft light because It matches my style and is extremely flattering for skin. Not only does hard light lead to more saturated skin tones, but it also brings out the rough blemishes in skin. Diffusers can help eliminate both of those problems! I personally use a Scrim Jim diffusers but in a pinch (or on a budget) you can use a thin white sheet too.
With indirect window light coming in from one side or the other, it leaves a hard shadow cast across the opposite side of your subject. Placing a reflector on that side bounces the indirect light back into the shadows and leaves you with that soft, even, flattering light. Moving your reflector closer or farther from your subject will control how much light is bounced back in. I use a 5-in1 reflector which gives you the option of white, black, gold, silver or translucent. They are pretty affordable and make great tools for wafting some wind into someones hair too. Win!