Series of articles - Create a series of articles on your blog if the subject you choose to talk about is an extensive one.
Don't just type, talk to your audience. Blogging is way big a market on internet and people will like you if you do more than just providing information. Suggest, express, appreciate, criticize and have an opinion to build a relativity to a like minded audience. Make them feel that their visit to your blog matters to you.
Newsletter: Newsletter is a great way to keep your audience glued on to all that is happening on your blog. It is best way to know who your loyal audience is.