Put on a nice candlelight dinner, some sweet music, breeding? forget the propholactics , ok bad jokes
Clean water, well planted tank, they prefer to spawn on rocks so add a few a few for choice. Ph level? under 7.5 is good, but the lower the better as more eggs will hatch. Raising the temp (30 degrees C) often helps to trigger a spawn, a 50% water change may help as well. Hope this helps
Andrew
edit in - oops nearly forgot to say, rams a bad first time parents, it may take them a few tries for them not to eat the eggs