This is a big question 😄 so I'm going to try and share some thoughts and if I ramble or something isn't clear, please let me know.
When someone opts in, deliver what you promised them. Whatever that lead magnet is. Then create a follow-up sequence that's intended to nurture them along.
They don't know you, so sharing that you have something to offer them before you build trust will be a turnoff.
Nurture that new subscriber through a sequence that spans 2-4 weeks. Each email has a specific and singular focus with a call-to-action. The goal of this sequence is to build trust and relevancy of content to gather up more information about the subscriber, so that when you are ready to pitch something, they want it.
The emails in this sequence fall into categories: permission (give the subscriber permission to be where they are), authority (share what you are known through other people's eyes...think sharing a podcast you were a guest on), training (quick tip or hack shown through a video), recommendation (share a resource that isn't your own), and ask (where you show what you have to buy).
Each email category is written directly to the subscriber (even the "ask" email). Keeping the emails "you" focused is the best way to build trust. It shows that subscriber that you understand who they are, what they are struggling with and because of that you have the answer to their questions (i.e. whatever it is that you sell).