Google Adsense you mean? Well similarly to how hubpages will pay you per impression or view, google adsense will pay you for each click on their advertisements.
The only problem is it's not often that you get clicks on google ads. I've gotten almost a couple thousand impressions on my hubs (and a few bucks) from hubpages but very few clicks on my adsense ads.
And no you can't really improve your ad revenue it's kind of a "get views and pray google had the brains to put ads that people will want to click on in your hub" thing.