Just optimize the keywords in your product data feed. Use the resources available on google and use sites like singlefeed and other resources/tools
yes. i have a great tip , use 2 or 3 word keywords in brand column, Atleast 3 times a 1 keyword must repeat in your products. You will see results in 2 - 3 days
make sure your product descriptions contain keywords you are targeting, make sure you map your product info into the relevant fields of the feed.
really annoying that product search comes through as natural traffic >>>> goes to analytics boards to vent.