It takes time. Some kind of competitive advantage over everything else in the marketplace will help to. People need a reason to bet on your company which overcomes the risk in instability.
As time passes and your service stays solid more people will come on board. Something like github is a good example. I doubt many big companies would have considered relying on them early on, but their track record has changed that now.
As time passes and your service stays solid more people will come on board. Something like github is a good example. I doubt many big companies would have considered relying on them early on, but their track record has changed that now.