There are many informative articles on how to start a blog.
You should start on a self-hosted platform to optimize for search engines.
This article lays out the steps:
- Choose a blogging platform (self-hosted recommended)
- Pick a domain name
- Get a web hosting account
- Install blogging software and set up a blog
- Select a blog design and layout
Google for 'How to start a blog' and you find many good ideas.