...as someone who happens to be extremely qualified to give long-lasting relationship advice...
First, as other people have said - we need to know how old you are. How old are you, and where are you currently in life? High school? Future plans...?
Secondly, what is she doing in life - what are her plans?
Without the answers to those questions, I can't give you a very detailed plan. But given what we DO know - I'll just say this:
FIRST AND FOREMOST: Do not consider dating anyone unless they are your best friend. The biggest problem people make these days, and why most of their relationships fail miserably, is that they consider dating an "experiment". It is not an experiment. You should never date anyone without acknowleding and hoping for the possibility of spending every waking moment with that individual, of marrying that person. If you consider dating an experiment, you don't love her, and your relationship's chance of failing increases a hundred times. If you're not giving it your all, the universe will know it, and through a series of events - you will lose.
SECOND: If you love her, you will be willing to wait for her. Not a week, not a month, but potentially years in order to be with her. If you love her, spending time with her, knowing that she is happing spending time with you, will be enough until you're able to guarantee you don't end what is ultimately the most important thing in the world to you. If she isn't your best friend as of yet, don't consider dating her, especially if you're in high school - because if you don't like them enough for them to be the most trusted and loved person in your life, then you're not in love and you're making a mistake. Once you've established what is your ACTUAL love for the individual, you'll be able to wait. And you can spend your life making sure she is happy, comfortable, and that she knows you're there in whatever capacity she needs you. You do not need to ask her out in order to wind up together.
THIRD: If you love her, you will want what is best for her - her happiness eternal is and will be the most important thing in the world. If you're not at this point, it's not love, and you shouldn't be dating her. And given that you want what is best for her, you don't have to ruin a friendship by asking her out - you can spend your time waiting for her. Let HER ask you out, in the event down the line that she wants to. This way, you guarantee that she gets what makes her happy. If she asks why you didn't ask her out, you can say that you wanted her to be happy in life, and that you wanted her to have whatever she wanted when she wanted it - and you didn't want to risk her happiness by asking a question that could push her away. This makes you covered, is the truth, and sounds sweet as hell from her standpoint.
If you don't love her enough to wait for that to happen, then you don't love her enough to spend the rest of your life with her.
If you don't love her enough to spend the rest of your life with her, or if you don't know her well enough for that, then you shouldn't even be considering dating her and should be spending all of your time getting to know her, and becoming the best friend she's ever had.
If you are presently incapable of acknowledging all this, and committing to something of that magnitude. You shouldn't even be considering dating - because it is not an experiment, it is real. People get hurt, people's lives change. Sometimes for the better - sometimes forever, sometimes for the worse - sometimes forever.
Do not make the mistake of every other guy on the planet, and give it your all. This is my advice. Follow it, and you'll likely wind up happy. Ignore it, and a TV show has your relationship's future outlined for you already.
Cheers.
Edit: Oh, I forgot to mention. There is a possibility, that even if you do love her enough to give everything for her happiness, waiting patiently, becoming her best friend, that you give up your life for hers - that she still will not feel that way in return. This is what you risk by loving, and you will very likely be torn to pieces afterwards. Some would argue that this is bad, but I would not. It will make you a better person, and let's face it...if you really love her, you won't be able to help it, anyway. Just thought I'd let you know.