The easiest way to find writers for publishing is to advertise where they look for publishers willing to accept submissions. Make it easy to find you!
Almost two years ago our (micro) publishing company went active for submission. It was very dry for a few months, then they started to come in. Why? We advertised on writer boards and put out notices we were ready for submissions. We made it easy to just complete a web form and submit. Our submissions email address exploded.
Now, we get on average 3-5 submissions daily. It takes no time to sift through those and find the ones which could possibly be publishable.
Could we get more? Probably, but 3-5 a day is good for us.
Advertise! Ask for submissions! Get out there and bang the gong!