"improve placements" as in move up the ranks? I didn't fully analyze your site but approach it like this: Analyze all keywords that come to mind. Not broad things like "coupons" or "discounts" but rather "longtail" keywords like "printable discounts New York", f.e. (bad example, I know). Then, analyze the competition for these keywords (figure out what sites are ranking if you type in the term in exact match in google). Filter out the "golden nugget" keywords (high amount of searches, low amount of competition, high monetary value) and start optimizing your site for it. Then get as many backlinks as it needs to get to the top spot. Again, look at what your competitors did, replicate their process and then do some more and you should soon see the light
Dude I like your ad placement... Link unit at the top will be perfect if you blend it with the background... Try horizontal banner instead of large rectangle because it will mix well with your text. Hope it helps
simple follow other success ad sense publishers ans also try to follow ad sense guide and ad placement map that provided on ad sense halp or FAQ section
I'd consider using the same colour for your Adsense URLs that you did for the coupon links on your pages. This will help them blend in. Visitors will also form the habit of clicking pale blue links, which is what you want.