it should not be progressive. you need to be direct with her. ask her out. if she's not interested you can probably still be friends as long as you don't freak out.

and don't go saying you love her, because you don't. love has to grow. you're really into her, you like her a lot, you think of her all the time- these are the sparks of love. this can (and will) happen with many, many girls. actual love is developed and it requires her to reciprocate. remember this, or you risk scaring her off.

rejection is one of the greatest learning experiences you will ever face. embrace the opportunity for such growth.