How does dressing up like a man help Rosalind achieve her goals in As You Like It?
During the time that Shakespeare was writing, there were lots of rules about courting for men and women, especially high born men and women such as Rosalind and Orlando. So, the disguise allows Rosalind, first and foremost, the freedom to speak franky with Orlando. Being dressed as Ganymede gives Rosalind an opportunity to interact with Orlando "man to man" as friends, rather than two young lovers under the scrutiny of convention. And it doesn't hurt that they are also in the Forest, rather than under the regulatory eye of the court.
When they meet, they are completely smitten with each other, as traditional young lovers in Comedies often are. So, I wouldn't exactly say that Rosalind's dressing as a boy "procures" the love of Orlando. He's already running around posting love notes to her on trees when she finds out he is also in the Forest of Arden.
What Rosalind does is school Orlando in how to be a better (not so cheesy) boyfriend. She teaches him to woo his lady (really her) in a sincere and heartfelt way. So that, at the end of the play when she is returned back to her female dress, he is, literally, the perfect man for her, since she has taught him to be the husband that she desires.