I'm still using Mailchimp, so the specific details of setting up a list will focus on that, however if you choose to go with another service, most of the principles in this course will still help (and each service has its own excellent onboarding videos to teach you how to use it.
Mailchimp is free for up to 2000 subscribers, which makes it a good service to start out on, but it's not perfect. $$
Mailchimp also recently added some nice looking templates, so you can make well-designed emails, but better-looking emails may get less opens.
Mailerlite is a cheaper alternative, that does have a one-click resend to unopens, and makes very pretty (nicely designed) emails. Mailerlite also has drag and drop landing pages, so you can set up a high converting landing page for your optin offer, without needing some extra service; and they even have popups. If I was starting over, I might use this (and I might still switch). $
ConvertKit is a pro option, with more functionality - but less design. You'll get more opens, and more clicks, if you stick with a simple, text-only template so it's like a casual email. ConvertKit is better if you have multiple funnels and products, so you can, for example, stop sending an email series to someone who has bought a product. $$$
If you're not sure, I recommend getting started with Mailchimp for now, and reconsider your options later once your list gets bigger.
Don't obsess about having the "best" newsletter service or thinking your open rates should be higher. The grass is always greener. Almost always, the real problem is poor cover design, lack of reviews, and boring blurb.
After that, you need to rewrite your autoresponder series and email subjects, and start out on the right foot by setting the mood and tone immediately. Don't just be another boring author trying to see books. Show that you're different from your very first email. Surprise and delight.