Choose sharp source photos with clear subject boundaries to improve the starting conditions for automatic background removal.
Look for separation
A subject does not need a completely white background, but its outline should be distinguishable. Look for differences in brightness, color or texture between the subject and the surroundings. A black jacket against a dark curtain provides less information than the same jacket against a lighter wall. Blurred edges and motion blur make the boundary ambiguous before the tool starts.
Compare candidates before processing
If you have several photographs, compare them at similar sizes. Prefer the frame where the whole subject is visible, important edges are sharp, and no foreground object covers the outline. Check small but meaningful parts such as the strap of a bag, a pet's ears or the corners of packaging. Avoid choosing only by expression or color grading when another frame has a substantially cleaner silhouette.
Imagine two photographs of a trainer. One has dramatic lighting but its dark sole blends into the floor; the other has softer light and a clearly separated sole. The second is usually a better editing starting point, even if you later change its presentation.
Use a realistic success criterion
Process the better source and inspect whether essential details survived. Automatic selection is an estimate, not proof that every edge is correct. Glass, fine fur and overlapping objects can remain difficult despite a sharp photograph. If the result loses a necessary detail, change the source or use an editor with manual masking. Do not disguise a damaged silhouette by placing it on a background that merely hides the defect.