So the first prerequisite is to know exactly what qualifications to look for in a spouse, and the second thing is to qualify for Krsna's mercy. That means sacrifice. We have to prove our sincerity by performing sacrifice. The sacrifice for this age is chanting Hare Krsna. In Vedic culture there are other demigods one prays to for a good spouse, but since we are only interested in Krsna, we should pray to Krsna. There is no harm in praying to goddess Katyayani for a good husband to help in achieving Krsna, but generally we should just chant Hare Krsna as attentively as possible. The prayer should be something like this: "My dear Lord, please give me a husband that I can help in his service to You. That way, I can also serve You directly through him, and go back to You in the end. I promise to serve him faithfully and never disturb his mind over petty squabbles that mean nothing. I don't care for my personal happiness since, I know that my serving a good husband is my religious duty, and will award me the perfection of life." For the men, they can pray to this effect, "My dear Lord, please send me a faithful wife so that I can better engage in your loving service. I cannot make it alone, and so need the help of a faithful companion to get me over these youthful years. I promise to engage in your service more and more as the years progress and I come closer to sannyasa. Then I will be able to fully engage in your loving service. In the meantime, I will take very good care of the woman you send me to take charge of, and I promise to never misuse or exploit her in any way. I will do my very best to take us both back home to You after this very life."