Two pictures with the same outfit, the same room and the same pose can feel completely different, and nine times out of ten the difference is the light. Most descriptions say nothing about it, so you get whatever comes out. A few plain words fix that.
Say where the light comes from
Light from a window beside you, light from a lamp behind you, light from overhead: each one shapes a face differently. Window light from the side is soft and flattering, which is why photographers love it. Light from behind gives a glow around the edges and a more dreamy feel.
Say what time of day it is
Morning light is cool and clean. Late afternoon is warm and golden. Evening under a lamp is warm, close and private. Naming the time of day is one of the quickest ways to set a mood, because it changes the colour of everything in the picture at once.
Soft or sharp
Soft light hides small things and feels gentle. Sharp light shows texture and feels bolder. If a picture comes out looking harsh, adding the word soft is often all it needs.
Keep it the same across a set
When you plan several pictures to post together, use the same light words in each description. The outfits and poses can change, but matching light is what makes them look like one shoot rather than a pile of separate pictures.
Write down what worked
When the light comes out exactly right, keep the words you used. A short line like soft window light, late afternoon, is worth saving, because you will want that feeling again.