Hands down I’d say the best thing you can do is research 1 primary keyword, craft an enticing article title that includes your keyword (though it doesn’t have to be an exact match), spend time writing your search engine snippets (SEO titles/meta descriptions), and by far the most important is making your content as VALUABLE as possible through videos, nice graphics, table of contents, bold/colors/styling, etc. Small things like keyword density barely matter.
Then once you’ve got your domain name and hosting sorted out, it’s time to pick a CMS, or Content Management System, that will let you update pages, build your blog and integrate with all the other services you need. It’s hard to go wrong with WordPress—the CMS powering close to a quarter of the internet. Keep in mind that eventually as you start growing traffic to your blog, you'll be wise to invest in a managed WordPress hosting plan from a company with great service like Kinsta, where all of the settings are custom-tailored and optimized to work particularly well with WordPress-powered websites.