Hi there -
There aren't any rules when it comes to optimizing a handwriting scan. In the PDF Optimizer, make sure the image settings are high enough that the processed page still allows you to view the text clearly. You can safely select all the items on the Discard Objects panel, as well as all those on the Clean Up panel.
The best thing to do is save a copy and try out the process. Be sure to check out the Enhance Scans tools as well, so you have the best scan of the handwriting.