The best thing about being a woman (besides the perogative to have a little fun ) is that each woman is unique. You don't have to be just like your sister to be beautiful. You are lovely just the way you are. All beauty is is playing up your assets, masking the things you don't like and learning to have confidence in who you are- and to love that person.
If you want to work on improving your looks, go for it! Experiment! If you've got the money, try going to a salon or make up counter and asking for some advice. If you're like me and don't have the money, magazines are (cheap) beauty tip treasure troves. Buy some mascara and eyeshadow and play with it! See what looks good to you. Almay has those sets for every eye color, which would be a great start if you're not sure which to pick. Wear lip gloss! Clear is always safe. LOL Who cares if you don't look just like the girl on the youtube video? If you feel good, you look good. Developing your own style will take time and trying different things, but don't let that stop you.
You can be beautiful, just the way you are. I wear make up and style my hair and I still feel like I look like total **** somedays. I hope you find a way to accept and appreciate your own beauty, my friend.