Decide which side is the subject
A rainy window offers at least two subjects: droplets on the glass and the scene beyond them. First decide which should look sharp. On a phone, touching a large droplet on the screen may help set focus, although some cameras insist on choosing the distant scene. Move back slightly or try a different droplet if the camera keeps hunting. You do not need an additional lens to begin.
Turn off nearby room lights when they appear as reflections. Holding a dark cloth behind the phone may also help, provided it does not cover the lens. Clean only the safely accessible inside surface with a suitable product. Do not lean outside to polish the outer glass. Working through a closed window is part of the point of this exercise.
Compose three different photographs
Aim for three pictures rather than fifty nearly identical ones. The first can show an isolated droplet against a fairly plain background. For the second, find colour behind the rain: an umbrella, a painted wall or a traffic light, rather than concentrating on recognisable strangers. The third can show the wider scene, including part of the window frame to explain your viewpoint.
Change position before changing camera settings. Moving a few centimetres places a different background behind each droplet. If a bright light becomes a featureless white patch, lower the exposure slightly on the screen. Avoid flash: it usually reflects from the glass instead of usefully lighting the street.
When the rain stops
Compare the three photographs on a reasonably large screen. Check whether the subject makes sense without zooming in and whether an accidental reflection attracts more attention than the rain. Crop to strengthen what you noticed, rather than trying to rescue every photograph.
You could keep a seasonal series from the same window, adding the time and one observation about the light. Before sharing, remove pictures that reveal a neighbour's interior, a readable number plate or someone in a private situation. Droplets, colours and shadows offer enough material to describe the weather without making other people the subject. Save the original files separately if you want to compare different edits later.
