Do you find yourself constantly asking...
1. Why does no one notice me?
2. How do I get the attention of this person?
3. Why do they always lose interest in me?
If so, then your issue is simple!
You expect people to pay attention to you. Now, this isn't a bad thing, but it won't get you noticed. Chances are, if you're falling into the category of having asked any of those questions, you are relatively shy or socially awkward. Now, I'm not a sociologist, I could very well be wrong. But from my observations on this website, in myself, and in the people around me, this seems to be the case.
The hard truth is: no one will just... notice you. You have to be notable; worth being remembered. No, you aren't worthless, but if you just blend in with everyone else and don't get noticed by anyone, you certainly don't stick out. That is an obvious fact. So what do you do? Well, you make yourself stick out! Whether it comes down to how you act, how loud you are, how honest you are, how open you are, or how you dress... you just have to let yourself stick out.
I used to be the guy nobody noticed or cared about. Then in High School, I joined the Speech and Debate team, drastically changed how outgoing I am, and started wearing a tie to school every day. *Insert someone shouting "Attention whore!" or "Hipster!" here.* No, no, it was a simple bet with one of my friends which just stuck. Now I'm in my junior year and everyone knows me for wearing my ties, being a relatively nice guy, and being great with my words. I stuck out.
Some of you... well, no, A LOT of you probably aren't in high school anymore, though. Soooo what? Wear a tie to work? No. Just crawl out of your shell and be more sociable. I'm not saying change how you think about things, just change how you act about things. You can still be the same you that you're comfortable with. Just let other people experience who you are more often. Sooner or later, you will be noticed for it.