welcome to womanhood, sadly its one of the things women have to put up with.
I remember the first time I was hit on, was an overwhelming experience, I actually did not know how to react. lol.. I remember making an excuse up and left.. My roommate (who is cis-female) laughed at me and said, you do know he was hitting on you.
But you can have some fun with it, I remember in my single days, i let the guys buy me drinks and i chatted with them, they got nothing more.. I could go out for a night and not pay for one drink, ok I did wear tops that showed off my D cup cleavage.
A tip to keep them away.. wear a ring on your ring finger, that keeps them away.. Since i have been engaged, no man hits on me.