Start with clear square artwork
Tiny icons cannot carry much detail. Use a mark or logo that remains understandable when reduced and avoid long text or very fine elements.
Check transparency and edges
If the source uses transparency, view the generated icons against both light and dark backgrounds. An edge that looks good on one color can disappear on another.
Do not judge only at 512 pixels
The real challenge appears at 16 and 32 pixels. Inspect those actual sizes instead of judging only from a large preview where every detail still looks sharp.
Test the pack in a real browser
After installing the favicon files on a site, clear relevant cache or use a private window when testing. Browsers cache favicons aggressively, which can make a correct new file appear unchanged.
Simplify the mark before shrinking it
If the source logo contains fine shadows, tiny lettering, gradients, or several competing elements, create a simplified icon version instead of scaling the full brand artwork literally. The goal is recognizability at tiny sizes, not preservation of every detail that works on a large banner. A deliberate small-size mark usually looks sharper and more intentional than an automatically reduced complex logo.
Verify the HTML and manifest references after generation
Generating the image files is only part of the job. Check the favicon, apple-touch-icon, and web-app manifest references and make sure paths and declared sizes match the files you actually deployed. Then test a normal browser tab, a mobile home-screen shortcut, and any installed PWA experience you support, because each surface may select a different icon from the generated pack.