I'm Founder to a new online application/website.
We have made modest progress in the past 6 months (just over 150 member sign ups). Given that we were in beta for the first couple of months, I feel "OK" about the progress.
It does fall far short of the critical mass we need to get to revenue; I'd estimate that to be at least 10X our current membership count. The good news? The trend is larger businesses are joining, which increases our reach.
As a general rule, would you focus on developing a more engaged connection with your existing users (or customers) or focus on getting more users? We have limited capital, so how would you weigh the two variables in terms of importance?
You cannot answer this properly without a full knowledge of the business.
Look at the expected and maximum costs, expected benefits, and worst case results of each choice, and consider the middle ground if possible.
It may be that either option you pick will be successful, it could be that the business is doomed and neither option will work, or it may be that the best option is some of each. Even after you make and execute a decision, you will probably never know for sure if it was the best option. So make your best informed decision, and do the best you can at its execution.
If your business model allows you to cross-sell or up-sell more products/services to your existing customers, I would suggest you to dedicate them a good amount of attention in order not just to increase your revenues directly, but also get word of mouth and testimonials from them to use in the search of more customers.
If you can't cross-sell nor up-sell, still think hard if you can leverage an outstanding service to your existing customers to find referrals and get more of them. If word of mouth can't make you grow very fast, it can very likely kill you if your customers aren't satisfied.
Why not both? By surveying your existing customers and finding out what they want and need, you can focus on making them happy. Also, get out there and find the innovators in the industry and market to them. Engage in discussions and find out what they want and need. Seth Godin goes into this in more detail in his book "The Purple Cow." If you get the innovators on board, they will bring the early adopters and everyone else.