The data only goes back about 1 month so first off i would start collecting it each month so you can begin to track things over time. This could help you spot seasonal changes.
I would then start by reviewing all the pages with high impressions and a reasonable average position as these should be easier to enhance and hopefully gain click through / rankings.
Pages with low impression but high clicks could point to more long tail keywords which i would not see as a bad sign.
You might also want to tie this in with your other keyword data to see if you are ranking / doing well for the phrases you would expect. This could also open up other opportunities for other content generation.
Also if you click through on the query you can get a better idea of the pages being served and therefore help to focus your efforts - it will also help identify if you are focusing keywords on too many pages.