Most JPEGs can be much further compressed without visible difference by applying MagiCompression. To MagiCompress the Image press the 
button on the Compress Image Control Palette. You can vary the amount of MagiCompression by dragging the MagiCompression slider. Values between 30 and 60 are probably best.
You can use the 
button to remove all MagiCompression, Extra Compression or smoothing.
If MagiCompression over does the compression in some regions there are three things you can do:
- Reduce the level of MagiCompression using the slider
- Increase the overall image quality with the JPEG Quality slide
- Remove or reduce MagiCompression in the effected regions (see steps 4 and 5)
Method 3 will usually give best results.
Step 4 (optional): Modify regions (Simple)