Well, the chasing is a start! The chasing is triggered by change in water temperature from cool to warmer. I have heard that it can also have to do with a change in lighting. I think fish normally breed in the spring, when the water gets warmer and the sunlight gets stronger.
Good water quality is part of the equation, and I have heard that feeding a lot of high-protein food will also get them to breed.
My fish bred and had fry when they were about 3" long, I thought they were too young, and to top it off, they were sharing a 10 gallon while my 55 gallon cycled. Now they are much bigger and older, in a much larger tank, they chase a lot, but no more eggs! So, I don't really know if there is a way to make sure that they breed... The only thing I can think of is I was doing water changes every other day because of the small tank. Maybe the water was super perfect?
Laura