Book

I want to write a book. I've always wanted to, you know, like a dream that one has for the future, when I'm older, wiser, etc. But recently I've been wanting to do it NOW. I know I'm not that old or wise, but when I think about some of the crap that sits on shelves at B&N, I think, "I can totally top that!" The problem is I don't know what to write about. I have a few ideas:

• Marriage
• I've been married for only 3.5 years, so I don't know tons about good marriage, but I know some things, some experience to share, some funny stories.
• Being an immigrant
• Due to my light complexion and my almost unnoticeable accent, sometimes people forget that I'm not from here. I've lived here so long, but there are somethings that I will never be a part of or relate to. Plus, there's a lot of ignorant people out there and I'd love to educate some of them with a little global exposure.
• Community living
• A little over a year ago, my husband and I got a roommate and six months ago, we got another one. This makes for a lot of stories about meals together, chores, games, friction, accountability and love.
• My crazy family
• but then I'd have to get a bunch of permission from them like the chick in the Glass Castle.
• Some other random topic that I know nothing about, but I could research. 

So what do you think? How does one start the writing process? Should I do that whole blog to book thing like in Julie & Julia? But my thoughts on this blog are so totally random, I don't know if I could put it all together to make a book about one topic. Maybe I can make a book the way they made Seinfeld: a show about nothing. Anyway, any advice would help right now.