Proper usage of keywords is a very important factor to consider. A lot of adsense sites have no relevancy as they mix a lot of irrelevant content. Keyword density also affects EPC to an extent. It's all about achieving higher CTR though. If you can achieve 20% CTR (my most sites do) you will make good money despite low EPC (not too low). To test anything, you need traffic. So focus on that.
If you can increase your CTR, your EPC could also increase. I was able to increase my CTR from 1.5% to 3.5% by optimizing ads and my EPC also increased by 150%. USA traffic also gives higher EPC.
Ad placement matters, go where the eyeballs are. You need enough traffic, over 10000 pageviews a day and you'll be making dollars not cents.
Very first thing to consider is quality of content next is placement of ads third thing to achieve is traffic don't rub after money try to provide useful information and you will make good bucks. adsense is super easy stuff if you are providing good quality content, information rich content design and looks of a site wont matter speed does matter
I guess there is no other way to get high EPC than choosing high paying keywords. However you can increase your CTR by using different techniques.