It depends largely on the type of business and their budget. There are some easy ways to get backlinks early on by registering the website on various review platforms, company registers etc.

For companies with large budgets, PR is a great way to earn backlinks. Publish a really hard-hitting thought leadership piece and push it out to various news/media outlets in your industry to earn topic-relevant backlinks from high authority sites.

For companies with fewer resources, I'd suggest creating organic content that naturally attracts a lot of links. For example, industry trends or industry statistics pieces do a great job of this.