1
Name the image problem
For a soft photograph, damaged portrait, or small source image, write down the defect you need to fix. Sharpening, restoration, and upscaling are different jobs; a tool that handles one should not be assumed to handle all three.
2
Check what access includes
Before uploading, inspect the destination's current terms for trial availability, export limits, watermarks, and any account requirement. A search result describing a tool as free is not evidence that your particular output is included.
3
Test against the original
Keep an untouched copy and compare the result at the size where you will actually use it. Look for invented texture, altered faces, halos around edges, or text that has become less legible.