Start with the right format
Use JPG for photographs, PNG for transparency and crisp graphics, and WebP for a balance of small size and quality. PNG is lossless; lowering a quality slider does not reduce PNG quality or reliably shrink its size.
Find your quality sweet spot
For JPG and WebP, start around 80% quality. Download and inspect fine details at full size. Lower the quality gradually if you need a smaller file.
Resize before you compress
A 6000-pixel photo is usually larger than a website needs. Resize it to the display dimensions first. Keep your original file so you can return to it later.