You can build your website or blog around general topics or niche topics. Generally speaking niche websites or blogs work better with Google Adsense. The reason for this is that the ad targeting is much better. In addition, as you have a focus on your niche your content will become better and unique, which will establish you as an expert over time and attract plenty of visitors.
If this is your first try at building a Goolge Adsense website, make it about something you enjoy and are knowledgeable about. It will make the process much easier and less painful to accomplish and increases your chances to success a hundredfold. You should however make sure that your topic has enough of an ad inventory and the payout is at a level you are comfortable with. What is meant is, that you need to establish if there a market for products and services and are they advertisers willing to pay for advertising.
There are bunch of tips and tutorials about AdSense, you can find here. But first of all you need to understand how Google Adsense works on your website or blog.
And once you did it, you are going to want to increase your Adsense revenue by using some high paying keywords, and you may even be tempted to buy a high paying keyword list. But be aware, there are some pitfalls. Firstly, there is no guarantee that the key words on the list are accurate or the payouts per click. Secondly, there is a distortion of the supply and demand relationship for these high paying keywords. Obviously, everyone wants ads on their website or blog displayed that make $35 or more per click, but the number of advertisers who are willing to pay vast amounts of money are limited and are only in high commercial value categories. So, the competition for internet traffic is going to be stiff and will cost you a lot of money in advertising to promote your website or blog.