Can I buy a list when I’m just starting out with email marketing? How should I grow my subscriber list?

It might be enticing, but you must reject it. Organic growth is the only method to obtain an email subscriber list that will benefit your business. To begin with, many email service providers would not let you utilize bought lists. Second, the email addresses found on such lists are, to put it mildly, not high-quality leads. Because they didn’t opt-in to your unique email list, they won’t contain individuals who are really interested in your products or services, and they’ll be far more likely to flag your emails as spam.
Offering an incentive in return for signing up to receive your emails is the greatest method to develop your email subscriber list. You may promote this offer on your website, on your social media sites, and on landing pages, you design to get people to sign up — just get the word out, and your leads will qualify themselves by opting in.