There are hundreds of free templates available online at various sites. You can search on Google and find/ download the template which you find is good for your blog.
Consider following factors while choosing the template:
Navigation: The template should be clean and it should make it easy for the website or blog visitor to navigate easily from one page/post to another.
Search engine optimized template: As far as possible, go for templates which are search engine optimized. This will help you to get more visitors from search engines to your blog.
Responsive templates: Choose a responsive template for your blog. It will make it easy for the blog/website to load on devices like mobiles and tablets.
Hope this response helps you!