When I was getting into the film industry as a young'un, the two people who had served as my mentors through an independent film gave me some terse parting words: "Don't get desperate."
It took me a while to understand what that means. It means don't take a shitty gig because you think you can't get a good one. It means don't humiliate or prostitute yourself to get a gig. It means that no matter how hungry you are--and you will get hungry--don't work for five bucks an hour, don't work where it's not safe, don't work where they don't follow the law. It means any time your instinct says "this is a screwjob" but your brain says "hey, it's work," it's a screwjob. It means always be able to say no.
And this is why I ultimately left the film industry--because I realized that unless you're talented, well-connected, rich, or lucky, (and I was 0 for 4), it preys on the desperate. Hollywood is full of producers, some of them quite big-name, some of them doomed losers, who think that you should be willing to do anything just for the privilege of getting their coffee--and it's also full of eager, desperate young people who bend over and grab their ankles and say "regular or decaf?" You don't sacrifice until you start getting respect, you just sacrifice and sacrifice until you realize that no one respects a sucker. In most industries that's where you simply walk away if you aren't getting respect from the start, but unfortunately in film there's a glut in the sucker supply so I ended up leaving completely.
Do I have to spell out how this applies to sex and relationships? If you're willing to do anything to get or keep a partner, there'll be some scary people willing to take you up on that "anything." If you think you have to humiliate yourself until you earn someone's love, you'll find the humiliation just keeps coming. If you're not willing to walk away from someone if they cross the line, the line will be crossed. If you settle, then what you settle for is all you'll ever have.
Don't get desperate.