I'm looking for specific steps you would take to choose between two possible subjects for a niche site. As an example, if the choice is between golf and horseshoes, seems golf would be a better choice as golfers tend to buy more expensive equipment, go to resorts, take extended lessons, buy videos as compared to horseshoe players who are a sorta frugal group. There are probably more adsense ads available for a golf site.
Problem is I'm not interested in either golf or horseshoes. However, I am fascinated with widgetball and gadgetball.
I've looked at Adsense Preview, Adword tools, keyword suggestors, bid tools, kei, overture, competitive analysis tools, etc. and am overwhelmed with all the data available.
What are two or three very specific things you would do if you were trying to choose between gadgetball and widgetball as the main theme of a site with the intention of generating some income from Adsense?