There are many different ways to approach digital marketing, and the specific business idea you choose will depend on your skills, interests, and the needs of your target market. Here are a few ideas to get you started:

1. Social media management: Many businesses struggle to keep up with the demands of running a social media account, and they may be willing to pay for someone to manage their accounts for them.

2. Search engine optimization (SEO): Many businesses want to rank higher in Google search results, and SEO is a good way to help them achieve this goal.

3. Content creation: Businesses often need high-quality content for their websites and social media accounts. If you're a skilled writer or video producer, you can offer your services as a content creator.

4. Email marketing: Email is still a powerful marketing tool, and many businesses need help managing and creating email campaigns.

5. Influencer marketing: The rise of social media influencers has created a new opportunity for businesses to promote their products and services through influencer marketing campaigns.

6. E-Commerce optimization: With the rise of ecommerce platforms such as Shopify, Amazon and others it's possible to offer businesses a optimization service, this include product page optimization, customer conversion, shipping and other related service

7. Online advertising: There are many different types of online advertising, such as search ads, display ads, and social media ads. If you have experience with any of these types of advertising, you could offer your services to businesses as an online advertising expert.

These are just a few examples, but there are many other opportunities in the world of digital marketing. The key is to identify a specific niche or problem that you can solve for your clients, and then build your business around that niche.