How can we compete with big companies on marketing when we are solo or very small businesses?

Large companies have large teams who market full time. Most of us don’t have that luxury. Just focus on one thing-selling to the right person.
Target your ideal client- you don’t need to sell to everyone. When you post on social media talk to them directly. Think about who you would love to see come in to buy your service. The more you focus the stronger your business and expertise will become.

Don’t get concerned that if we don’t advertise to everyone we won’t get clients. Make yourself the expert in a small area of your ideal clients and the business will come to you!