Society and the Single Girl: When Is Someone Interested?

I can honestly say that when it comes to love and relationships, I lack the knowledge to "seal the deal." The deal being getting someone into the Facebook official relationship where they are your boyfriend, girlfriend or significant other.
I think the struggle comes from the fear of being wrong. I've been rejected so many times through out my years of high school dating. (Pretty much my freshman through junior years.) And when you assume things, well you guys have heard the saying. Whenever I asked someone if they liked me, I remember the intense awkwardness and nothing was the same ever again. Of course, I wanted to maintain a friendship with the guy, however, it just never happened.
As I enter my last year in college, I'm realizing the reason why I am single is because I never take that leaps I did when I was younger. I'm too afraid to ask someone how they feel about me, because I am worried that they will reject me. Sad, but true. I worry someone may or may not be flirting with me, and whether or not I'm taking something that may not be flirting as flirting. This sentence was as complicated as my feelings are.
The thing about dating is finding the courage to tell someone how we really feel. That's my biggest struggle. I know how to ask for a job, and to annoy the people involved until they give it to me. But dating is a completely different ballgame. How do I let someone know I'm interested without coming off as too obvious or too desperate? How do I get the nerve to tell someone how I feel without coming off as an idiot?
This is when real life and romantic comedies diverge. In a romantic comedy, the cute dark haired stranger who takes you to Dublin is your soulmate. Or in a romantic comedy, you fall in love with a cute dance instructor. In real life, someone whose attractive in your class who asks you about the readings may just be interested in being your friend. Or, someone whose meant to be with you may not be for whatever reason.
The last time I was in a relationship was when I was about 15 years old. I didn't know much about relationships other than I should have one and that Bella Swan was a good role model to have. Let me say at 21, I have grown from that concept of love. I want to be with someone whose my partner. I want to be with someone who supports me, my aspirations and dreams. I want to be with someone liberal, who will accept the fact my closest friend is queer.
The thing is? I don't know how to get there. I don't know how to ask someone out. I know how to ask someone to hang out, but then I worry if it's a hanging session between friends or an actual date. Maybe the take home lesson is to take more chances, to vocalize your feelings and to maybe stop watching so much Netflix over the weekend. Where is my Prince Charming? Why can't he just magically appear out of the wood work and help me avoid this guessing game.