Before you start choosing a domain name and theme, you need to figure out what topics your blog is going to cover. What are you going to write about on a regular basis? You may already have an idea in mind, but if not, I suggest doing some intense brainstorming. Write a list of your passions, hobbies, and dreams, and a second list with your skills, experiences, and areas of expertise. Then start thinking about possible blog post ideas for each topic. If you're coming up short on article ideas, it's probably not the best topic for a niche.

If you entered a new domain at the beginning, it takes 2-24 hours for it to become fully registered. When it’s ready, Bluehost will switch it for you automatically. If you used an existing domain or opted to choose a domain later, you can set it up when you’re ready. (If you’re unsure how to do that, call Bluehost support and they’ll walk you through.)
Talk to people about what you’re doing: It might seem too simple, but tell the people around you what you’re doing. Get excited about your blog and share the things you’re working on. As Gaby Dalkin of What’s Gaby Cooking told me: “Maybe it’s just your friends reading you to start, but you should be responding to every comment and going out and commenting on other blogs. This is essentially your industry and these are your coworkers.”
Although I do think conversions are the most important thing I can recall when I first started out one of my sites and I was starting to get regular daily traffic of around 10 uniques, and then I had one day that spiked to 200. That was a very encouraging day. Just seeing that traffic spike gave me confidence and a drive to work harder towards my next goal. I had not made any conversions yet, no money. However, seeing that my hard work was doing something was very encouraging.
Lets say, for example, that you refurbish and resell used smartphones out of your home. You could use a blog to attract visitors to your website where you list your current phones for sale. Your blog might cover topics about DIY refurbishing. On one level, it seems counterintuitive because you want people to buy your phones, but it also helps you build a brand and gain recognition. Social media guru Jay Baer explains the concept on Copyblogger: