The Plant Doctor works from the photo you give it. A blurry, dark or far-away picture leaves it guessing, and when it can't tell, it says so instead of making something up. A few small habits make it much more useful.
Use daylight
Take the photo near a window, in daylight. Indoor lights tint leaves yellow or orange, and a flash washes out the spots and marks that matter most. If the first photo comes back unsure, "scan again in daylight" is the first thing to try.
Get close to the problem
Fill most of the frame with the leaf, stem or spot you're worried about. A photo of the whole room shows the plant is there, but not whether those spots are dry, wet or shaped like a fungus.
Show the whole plant too
After the close-up, take one of the whole plant. Shape, drooping and how much is affected help tell a watering problem from a pest or a light problem. If you add a note about when you last watered it, that helps too.
Check the underside of the leaf
Many pests live under leaves. If the top looks fine but the plant is struggling, turn a leaf over and photograph that.
When it says it isn't sure
The answer comes with how sure the Plant Doctor is. If it isn't sure, it will ask you a question or two, or tell you the photo isn't clear enough. That is the right answer to a hard photo. Take another one and try again, or ask a follow-up question in the app.
A photo is a good guide, not a lab test. Roots, soil and the weather around your plant matter too, so treat the answer as a first step and watch how your plant responds.