The total size of your images should be under 30K. Consider optimising your images for size, combining them, and replacing graphic rollovers with CSS.
The total size of external scripts ideally should not be over 8K. Consider optimising your scripts for size, combining them, and using compression where appropriate for any scripts placed in the HEAD of your documents.
The total size of your external CSS should be under 8K. Optimise your CSS for size by eliminating white space in the code, using shorthand notation, and combining multiple CSS files where appropriate.