I can tell you that you definitely should not enter into a serious relationship as your birth sex, or with someone who identifies as primarily attracted to your birth sex. Female partners of both trans men and trans women seem to adjust much better than male partners on the whole, but it's still not easy or fair for them, and the resulting relationship is unlikely to resemble the original.
But there's no reason you should avoid casual dating. And if you have the chance to enter into a relationship with someone who sees you as your target sex (and for whom being attracted to your target sex is consistent with their identity), there's no reason not to go for it if you want to.