I'm not one to give advice, since I don't have a blog of my own. But I'd assume you want to look for an area where (a) you have a natural interest, and (b) for

I'm not one to give advice, since I don't have a blog of my own. But I'd assume you want to look for an area where (a) you have a natural interest, and (b) for which there aren't a lot of existing resources online.