Clean up the map to increase the visual impact.
Work with colors, shades, font sizes, placement of labels, legends, titles and legends.
Add icons, legends and explanatory text as necessary.
Select colors which also show well when printed in black and white laser printers.
Ensure all maps meet a set of requirements e.g. disclamers, scale, direction etc.
In general, I export/save my GIS output in PDF format and then open the PDF files in Illustrator. While there may be a way to preserve the layer information, I generally output the GIS layers as separate PDF files and pull them into Illustrator as layer files. I will send you PDF files (which Illustrator can open dorectly) and I expect to receive bacl illustrator files back.
For an idea of what involved, I am enclosing a word document which contains 7 maps in BMP format.
While I have never posted a task and invited bids, but have worked with off site freelancers for quite a few years and very comfortable with the arrangements. Please get back to me for clarifications.