How to write characters of a different gender than yours

AtStar Trek Writer's Defense of Diversity in Sci-Fi Is Damn Near Perfect,PV said,

I don't think I could ever write a convincing same-sex relationship. I'm just not wired that way. But I totally support and encourage those who do - even if that kind of relationship doesn't interest me personally. The reason is simple, if we want a better world for ourselves, we have to have a better world for