My sister was a cheerleader at my school last year, and everyone was all over her! When I came to the school that next year, I didn't have any friends in my grade, but all the 8th and 9th graders want to be my friends, I even had 3 guys in the 9th grade ask me out, but I think that they only like me because of my sister. And I lost all of my friends in my own grade because of it, the group I hang out with is a bad influence, and all the guys are perverts to me and I hate it! What should I do??

Find new friends. Assert your own personal self so that you're not in your sister's limelight... it's good to have your sister "make" connections for you, but only use it to benefit you (teachers... etc), not with her "bad crowd" friends. Assert yourself and be you, and maybe people will notice that you're your own person.

Be yourself, and try to stick to the good crowd. Is your sister in with the bad crowd? If so, it will take her quite some time to get back to being respected. Sounds as though she may be a little, umm, easy or acting that way. Don't make mistakes that you know better than doing in the first place.
Remember, "An ounce of prevention, is worth more than a pound of cure", unknown author.

Just find a better, more trustworthy crowd and ignore them. You could do better.

First no you did not lose any of your old friends because of the new people, you chose to dump your old friends for the new people.

Next you are not your sister and what is going to happen when they move on next year and the next, and you don't have older kids to hang with.

It is not easy but time to start going back to your old friends and telling them you are sorry and start being with your own group.