I am a software engineer turned freelancer, and I started a company some time back with a friend.
I am good at making stuff and my other co-founder is good at design & research.
We have a couple of clients right now that are helping us pay our bills and take care of a couple of employees (excluding us).
Obviously, for increasing the revenues we should focus on increasing the sales and marketing. Right now I am not sure should I focus on just catering our existing clients(which is a risk) or should I spend time on some other activity too?
PS: We provide Web design and development services to our clients.
I'll just suggest reading The E Myth which covers this topic quite thoroughly.
https://www.amazon.com/Myth-Most-Businesses-Dont-About/dp/08...
but the tl/dr; is something like "make time to work on your business instead of always working in your business. To that end, make things as process oriented, repeatable, and automated as possible".