When you do find the trends, you can also narrow it down by selecting a niche. Do you wanna tackle mobile apps? webware? software? When you're more specific, it's easier to grow and maintain a following.
Ronique Gibson in his blog (probloggerdotnet/archives/2011/03/21/choose-a-blogging-niche-you-can-expand-on-for-life/) gives some tips on how you can choose a niche that you can go on and on writing about.
Enjoy and good luck with your blog.