You should probably focus on content first and see how will things progress. If you will have a lot of visitors for very different keywords, AdSense may be working well for you. If you got lesser amount of visitors and very focus group of visitor which may be willing to buy something you are reviewing, presenting etc., Amazon or eBay can more profitable. If you don't have any traffic, focus just on content.
It's a never ending learning process. Write - test - analyze - write more - analyze more - test - etc.
Before you make at least thirty hubs, don't count on huge numbers anyway. I hope this helps you:)