An important tip that I read in the article “How to Choose a WordPress Theme” from Bluehost Blog is that you need to choose a theme that is mobile responsive. More and more people are accessing the web through smartphones and tablets. Having a website that is responsive to those devices will ensure that your site is accessible to the greatest amount of people.
One resource I found for free WordPress themes was themegrill.com. Their site offered a list of over 60 free WordPress themes and have them broken down by type of business they were originally used for. Of course, you don’t have to have the exact same type of business to use the theme. https://themegrill.com/blog/free-wordpress-themes/