Hello, hello! Here, I will share some questions I ask myself when making image descriptions. Make sure to remember that these are personal questions, and that they may not work for everyone — remember to find your own way to work with image descriptions, as to be accessible for yourself too.
What is this? — A divider, banner or icon? Maybe a replycon? A flag? A drawing, an animation? A graphic element? Is it commonly referred by with a specific name/term? Is it decorative or informative?
How is this? — Is it round? Is it square? Does it have a specific geometrical feel to it? Is it sharp? Is it soft? Is it a multitude of shapes? What vibe do these shapes give me? Is it classy? Is it cyberpop? Is it minimalistic?
What colours are here? — Multiple shades of pink and yellow? Which && what names? Vanilla cream? Burnt yellow? Hot magenta-ish pink? Is it light(est/er/ish) or dark(est/er/ish)? Is it vibrant, neon or bright? Is it pastel, or a baby tone? What objects reminds me of this colour? Is it a gradient from (COLOR A) to (COLOUR B)?
How many details? — Is there additional images? Is there a symbol for the flag? Are there other shapes in the image? Does it have any outlines or stripes? Is thetr a gradient? Is there anything overlayed on it?
Who's this? — What character is this, from what series/media? What is their expression, and what may the expression possibly mean? What are they wearing? What is their stance? What are they doing?
Where's this? — Is it daytime or nighttime (if you can tell)? Is there a specific natural landscape? What does the landscape have, trees and flowers and some birds? How does the mountain in the distance look? Is it indoors? How does the room feel, scary or welcoming or home-like or official/stablishment-like? Does the room have any furniture? Which, and how do they look like? Is there any animal or critter in the image? What critter is it, and what does it look like?
Now, obviously, the amount of these questions being answer varies depending on how complex a image is — please remember to keep in mind that plain text must also be accessible to people who are reading it — a lengthy, continuous huge wall of text may give headaches and confuse people. This is also not a extensive list, and additions in the notes are more than welcome. Make sure to only answer anything that gives key information, if you'd prefer to keep it short and sweet... Toodle-o!