Why is getting a date so hard? m18

I'm in my senior year of high school and never had a hard. I mean, I've hardly ever even kissed a girl. It's like every time I try to date a girl that I think I would have a fair chance with, she turns out not to be interested or finds another guy in the process of me trying. I don't know if I just have horrible judgement or if it's something I do while trying to talk to her. Recently, I tried for a girl who I thought would easily date me. I bounced her around in my head for a month whether I should go for because I had a larger crush on a slightly more "popular" girl. I decided to go for her but like all my other attempts, it ended flat. It ended with her being hesitant to Skype with me and then me just telling her that I liked her (all over Facebook). I don't know if there's something wrong with how I talk to girls, if I'm flat out ugly and don't realize it, or I just have horrible luck. Please help me out. I don't want to go to college like this.