I want to start writing a blog about technology. Where do I begin? Create a site from scratch or use CMS? Or use a site builder?

Use WordPress. Use a shared hosting company that offers preconfigured WordPress installations.

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.

Choose blogging platform then find the host & pick a domain name then started with WordPress

You can start with Joomla.com, Wix.com, there free plans are good for newbies, Or try revglue.com, wordpress.com, sites.google.com for more dynamic cms features.

Create one wordpress domain with hosting then start blogging post