Many of the following points apply to ALL people. But I am specifically focusing here on your interaction with women and girls. We live in a world where, unfortunately, there is a bias against females that takes the form of unequal opportunities, pay/compensation discrepancies, unfair judgments, objectification, etc that tends to benefit males… It is frequently demonstrated that although a female may be more deserving or more qualified… she may unjustly end up with less than she deserves.
Try your best to be aware of this bias. Be kind and chivalrous to women (even if chivalry seems dead in the people around you). Do not hesitate to offer help to a woman. But, if she declines your help, then respect that also and don't assume that all females are in need of rescuing. Some of the strongest, most intelligent, most inspiring people you will meet in your life will be women. Look to history for some examples of great women. Study the great women of our ummah, Fatima az Zahrah and the Mothers of the Believers (may God be pleased with them). Look around you in the present time to see and learn from great women. The first person who ever taught me the ahkam of tajweed (rules for Quranic recitation) was a learned woman. Many of your teachers and professors will be women. And of course, reflect on the rank of your own mother, and ponder why the Prophet (peace be upon him) said that Paradise is at her feet.
Understand that the Prophetic tradition demands love, honor, and respect for women. The Prophet (peace be upon him) valued the contribution of women to society, and he valued their presence, their opinions, and their beauty.
Keep in mind that every person has something beautiful about them. Treat everyone with respect and acknowledge their beauty. They are the children of Adam and Eve and were all ennobled by God… even if they may not know it or may have forgotten it. Because of this reality, all women are beautiful. Whether they are your classmates during your school years, or your professional colleagues later in life, you should remember that each and every female you encounter is a beautiful person.
You will start to notice, early on (even in grade school), that some girls are treated "better," some are ignored, and some are treated quite badly all based on other people's opinions of what is "pretty" or what is "ugly." Don't fall into this shallow way of thinking. Each and every girl you interact with deserves your respect and should be treated with kindness. Don't ever make fun of someone for having certain characteristics or traits. You will be faced with a lot of social pressure to conform to these judgments of people's outward characteristics. Other guys will try to convince you of this.. even some of the women will play along with these notions of defining beauty through a limited and superficial lens. You must defend anyone who is ridiculed for these reasons, and never participate in hurting someone's feelings.
Remember that there are some people who outwardly seem "pretty" but inwardly are horrible. Likewise, there are people who maybe don't have all the stereotypical features that are deemed "beautiful" by others, but inwardly they have personalities that will cause your heart to shake in awe of the grace and beauty God can put in a human being. Most people have a mixture of attractive and unattractive qualities, inwardly and outwardly… and we are all imperfect beings with a breath of the Divine in our lives. While remembering this, it is your job to keep an open mind and heart when dealing with others.
If you can do this, you will start to see beauty where you may not have expected it. You will be amazed by the number of beautiful women and girls (and more generally, beautiful people) that God has placed on this Earth.