This tip will increase your earning by 40% I Have seen that using only Medium Rectangle (300 x 250) and Large Rectangle (336x280) increases attention of website visitor by 50% so applying that my earnings increased 40% in last few months.
I think it hugely depends on the layout of the website the ad is being displayed at For example, with my website, 250 x 250 ads achieve the best results Some other people may argue that 728x90 are the best etc..
not necessary, but you can use mostly txt add and tragatted traffic specially USA and UK, you can earn minimum 1$ for each click.
Well , bigger ad = bigger chances for people to see it. And a lot of things depends on website template, so ad size mostly doesn't mean a lot.
This is not always going to be the case, obviously there are many other factors that you have to take in to account. Fwiw, and although "spammy", I've found that stacking two big blocks and placing them either on the left, right, or middle of the top your site will get highest CTR. This is because they are the first thing the site visitors will see. Of course, if you are concerned about the quality of your site, you would not want to do this.
It's different for everyone. No one can guarantee what will work for someone else. The only way to find out is to test it yourself.
That's strange. Lat month I actually removed a 336x280 and didn't replace it with anything and I got a 13% increase and my traffic is more happy!
I think people start clicking when they see a change on the web page. So keep alternating the placement of ads once in a while