I haven't really bothered looking at optimising it for a long time as it isn't really worth it any more for that venture, my time is best spent elsewhere. However, this is what I did know that is probably still applicable.
It is a chicken and egg scenario unfortunately that screws new sellers/listings for ranking...
Conversion is a big ranking factor for best match, so creating listings that renew are key, then leaving them to build (cross-promoting listings helps but as they have now stripped javascript that may need to be done manually).
Also quality of image and then listing needs to be considered;
a) Image - design the main image so it stands out when shown on the list, thus enhancing the ctr on impressions. Also, three reasonably sized images is the sweet spot, they lower the quality score of the listing if there is just one image.
b) Quality of listing - to increase conversion once a user clicks through.
Obviously, keyword stuffing the title is still relevant (needs to be very carefully constructed) and make sure he adds all the extra data and barcode number UPC etc.
You get a bump with fast and free shipping.
Price seems to also win out, whether this is in the algo or due to higher conversions, I am not sure, but the cheaper products end up being listed higher.
Hope this helps and good luck, the traffic is nothing compared to what it used to be so it may not even be worth his time working on it too hard.