I want to make an ask blog. But I don't know how to start it off, what should I do?

Well, the first step is choosing a character you like. Or make your own. The introduction should be a look at the character, and a brief introduction to who they are. Maybe even throw in a secondary character. 

As for story, throw some ideas at a wall. Don’t stick to anything yet, but ponder on multiple things. Don’t worry about getting a tad cliche.