Install a relevant WP theme
This topic can be a time consuming area and there is no definitive answer on to which WordPress theme you should select. But you should focus on the “type” of the blog you are running and the theme closely associated to help your blog.
Some of the broad blog types are personal, information portal type, news/magazine based, landing page type (to sell a product or service)
There are thousands of free themes and paid themes, but there are ones that are very well coded, tested and trusted by millions of users.
From those tried and tested themes, Im just listing 3 free themes and 1 paid theme (which I am using in this blog)
Top 3 Free WordPress themes
Perfect clean and fast loading blogging layout with top notch SEO features in built
For a Magazine styled blog
For landing page styled Blog and more advanced customizations
The only paid theme I recommend is Thesis theme (affiliate link), which is the #1 WordPress theme that is performant and offers best user experience. and because of these two major benefits it is best performing when it comes to SEO as well. I only use Thesis theme in all my blogs, no second thoughts.
Note: You can click this affiliate link and buy focus theme and you will get both focus and thesis themes. Just use thesis theme alone. You get top notch support from Chris pearson himself or you can also reach out to me