http://www.shrimpkeeping.com/ and maintain stability. Provide enough surface area for beneficial bacteria to grow and you'll create a healthy environment for these guys to feel comfortable in. Aim for this as the ability to breed is only a result of this.
The days of higher grades being harder are sort of over, if you can breed a decent stock A grade, you can breed a decent stock SSS+. The key is decent stock coming from someone who add's new genes to their breeding, culls defects, etc.
Even the past 2 years, taiwan bee's have gotten a lot easier to breed.
20g platy, , 2 x 10g shrimp, 3 x 20g shrimp, 7.5g shrimp and 1 great dane/mastiff puppy.