The first thing which comes to your mind is whats the use of testing when we have already placed 3 Text ads and 3 Link ads which are the maximum allowed on a web page. We can obviously expect the maximum earnings but you may be wrong because Testing is very important in adsense and basically it does not cost you much right? Its not only with adsense but its a general advice for any advert placed on a website. Always try to change the ad formats, placement of the ad formats etc.
Selecting the Best Ad Format : Generally peoply try to use a lot of ad blocks next to one by one in a hope that this could lead to a higher CTR but at times this works on the other way and the visitor may just try to avoid that whole section. Instead of keeping two 250×250 ad blocks next to each other try to keep only 1 ad block on your page. Try to use both Linkads and blockads at the same time and try using different techniques and if possible try to change the ad colours/ block size regularly because this can attract the regular visitors and give them a fresh look. Also try to get more tips at adsense resource section and learn about new adsense ad formats
Understanding your Audience : Take a example of this following screenshot which i have just taken from a website which is related to ‘Java’ , and you can easily find that this site is full of ads, but there would still be no problem because even though we ‘Webmasters’ would think this site as a MFA because of the placement of lot of ads. This is because this website’s audience is complete programmers and they have no idea these are adverts and this is the reason they would click on the ads and make the website owner more richer. If your website audience is SEO/Webmaster related who knows about adsense any type of Smart ad placement wont increase your revenue since its a fact that a webmaster would not click on other webmaster’s ads.
Understanding your Niche : Niche is very important because your total income would be dependant on this factor. Generally people keep searching for high paying adsense keywords to start websites but in general Entertainment niche sucks because they pay very less and the reason behind that is conversions in buisness/ROI. If there is a finance related website advertising their products they can expect a good ROI because they are expecting a sale of some product and hence they can obviously pay higher in adwords in order to get more traffic and conversions, but entertainment niche advertisers just need visitors for branding and increasing website popularity and hence they are the ones who look for high traffic which may be of any kind and this is the reason they bid very less and the same is affected to the adsense users who get paid less.