How to advertise my SMB?

You can go inbound or outbound channels.

Trying online marketing is good. You can create a simple website and introduce your services or product. If you have a website, you can try contextual advertising. Another way is to promote your business in social medias. But don't forget about your potential customers. The best way is to provide valuable content for them. If your website contains information only about your business, it will not attract many customers. But if you focus on the needs of your audience, they can come to your site, and some of them will order your product or service.