When you go with free, you’ll have a lack of control over how your blog looks and acts: Free blogging services (like Blogger, Medium or Tumblr) will pretty much always limit the design and functionality of your blog. This means you won't be able to make your blog look like your favorite other sites. Plus, you might not be able to do the things you want (like capture email addresses from your readers using tools like ConvertKit, include ads, join affiliate programs and other activities that'll help you actually make money blogging).
One of the important aspects that you should look for is the uptime of the provider. Search around and see if there have been any major problems associated with that hosting provider. Search for reviews and decide on the price point you're willing to spend. You should also ensure that the hosting provider has a WordPress plugin if you're not all too familiar with setting up software such as WordPress on a hosting account.
Working with advertising networks isn’t your only option when it comes to selling ads. If you end up with enough traffic, advertisers may come directly to you and ask you to place their ad on your site. You can also contact advertisers yourself. The biggest difference from the above mentioned option is that there is no middle man, which means you can set your own ad rates.