What Dani said. Registering a domain name is cheap and easy, finding a web host that supports WordPress ditto. Which would just leave you the job of fidning the right WordPress template and getting a little creative to make it your own; again really easy. The hardest part is creating the content that will drive people to your blog once it's up and running.
Well starting a blog is not that difficult job anymore because now several WordPress hosting provider allow you to deploy WordPress on one click with some predefine search engine friendly settings.
I would recommend to write down your online objective like: What are the core areas you will be writing about.
You can select any blogging theme free or paid totally depend upon you. I would like to suggest to pick a quality hosting provider rather than shared because usally shared hosting cause a lot of problems in long run.