This error message may appear when trying to upload an image:
“Sorry, you have filled your storage quota (250 MB).”
Using Photoshop’s Save for Web… option.
Vector type art can be saved as .png or .gif, photographic images can be saved as .jpg.
Ideally the images should be 72 dpi and not be wider than around 900px.
The only exceptions for optimisation are when an image is to be used for print – in which case it might be better to share it using a different medium than the blogs.