I've had my fair share of crushes inside school, but I never could break the ice and actually take any of them on a date until I realize what I was doing wrong. This is no guide on how to completely get a girlfriend but rather tips on how to get someone you like to start liking you back - They've worked for me, I'm suspecting they could work for you. This is done in the point of view of a guy, but some tips (maybe all) can apply vise versa.
1 - Sound Intelligent
No girl wants to date or even start liking a guy that has less brain cells Sarah Palin, so you need to at least sound like you know how to use your brains. When she says "Hey", immediately say hey back without thinking about it and if she starts a conversation with you you have to hold it. This implies that you're social and that you've evolved if you just stand there like stand there like a mannequin she's going to think you're a professional idiot. You don't have to be an Albert Einstein to attract the person you like nor do you even have to have the best grades ever, you just have to sound intelligent and use good social skills.
2 - Sound Funny & Interesting
No girl or person in general wants to date a guy that sounds boring. We all want to date someone that is interesting, funny, outgoing, and overall a good person to be around. Don't be one of those saddies that claims "nice guys finish last" when it's a load of crap, being nice doesn't entitle you to a girlfriend you should be nice because it's the right thing to do not because you want a girlfriend.
3 - Dress Nicely
Another thing that can enhance your physical appearance is your clothing. You have to find a good style that suits you and more importantly looks good on you, don't come to school wearing light-up sketchers if you're trying to attract a girl - In a perfect world this would be perfectly fine, but this is reality. Again you don't have to go above and beyond and come to school wearing Gucci, but you should make sure your clothes are a good brand and or look good on you. I've seen people wearing 50 dollar outfits and they still look like some of the most classy people in my school, why? Because the clothes that have on looks good on them but may look horrible on someone else.
4 - Accept & Love Your Flaws
This is the real world and some of us are not as physically appealing as someone else, but this doesn't matter as long as you personally love yourself. In other words, you need to have confidence and recognize your flaws and either accept them and or try to fix them to the best of your ability. No one wants to date someone that continually cries about how they're not good looking or good enough, period. If you think you're truly ugly or average looking, suck it up and accept it and love yourself for who you are. This is fact, you need to love yourself and be yourself and don't go to extreme and try to be an entirely different person because it's really easy to tell if someone is just doing an act.
5 - Last but certainly not least, HAVE GOOD HYGIENE
This is the most basic tip but for some people it's as hard as comprehending calculus. Please, for the love of all that is good, do not go up to someone smelling awful. This is what can get someone to disregard your attempts the very second they smell your bad b.o, make sure you smell right make sure your breath is clean - this should go without saying ... but you would be astonished at how many people leave their house smelling like they shower with rain water. So again make sure you smell great because you shouldn't go up to someone you like with your breath smelling like it died and decomposed 2 years ago they you're wondering why there eyes are making tsunami's. Also if you're the person being crushed on don't feel ashamed to tell someone they smell awful, tell them to have a mint or to go oxy clean their throat because they clearly don't realize this and have to be told so you're actually helping them.
I just wanted to share my own personal insight on this whole subject and I hope I've helped you the next time you try to attract your crush.