When creating images for the Web in your image editor (Photoshop) remember these things:

• Select the "Web Only Colors" box in your color picker
• Always keep your original Photoshop image un-merged in a separate resource folder for use later
• Do not change and re-save jpg images or gif* images(go back to the original Photoshop file, make changes to it, then save this new version). Changing and re-saving a jpg can cause:
  • -loss of data
  • -increase in file size
• Last step, before you post your images is to optimize them. Always save copies of the second to last step version of the image in your resource folder just in case your optimization tool does a poor job with image quality.

General rules for choosing file type

* If you must change a gif image, convert it to RGB mode before making any changes then convert it back to indexed color before saving as a gif again.