A free cold email course is coming in the next few weeks. Until then, I've put together a list of helpful resources on various parts of the cold email process:

Please don't just copy-paste templates and expect them to just work. Use them for inspiration, but there is no substitute from understanding your audience and crafting a message that is customized for them and them only.
Here's a huge list you can use for inspiration:

Knowing who you're speaking will generally define the quality and the results you get with your message. That's why building customer profiles is a great practice when cold emailing. Helpful resources on the topic:

Most of the people won't reply to your first email. They will usually won't even notice your first email. So it's your responsibility to try for several times, ideally leaving some time between attempts, to try and catch them at a convenient time.

We have to make it as easy and as quick as possible for the recipient to read & quickly understand what we're trying to say. And "readability" is a score for exactly that. Here's how you can improve the readability score of your emails:

Email servers try to block spam, so if you send too many cold emails at once, your message will get straight to the spam folder.
Warming up your email account is mandatory before sending cold emails, here are some helpful resources:

Some technical settings that are used by the receiving email server to decide (among other criteria) if your email is spam or not. Here's how to authenticate your emails, for G Suite:

As I previously mentioned, warming up your account and authenticating your emails are just some of the best practices to avoid the spam folder. The below resources cover the rest: