What are good filters to avoid following bots?

I know a lot of people say that you should not follow people without profile pic but I don't find that to be true on other social platforms. A lot of people who actively comment my posts don't have a profile pic. What are some other known ways to filter out bot accounts?

Thanks!

Don't follow people who have a ton of following?

You can't avoid it completely, but you can minimize it. Like using "remove users with no avatar", "remove users with links on their tweets" etc. option, http://twittermoneybot.com/ has these features.