I went straight into HS acting all confident, ****y and stuff. I thought I was so popular, met everyone. After about a month, unless you play on the football team, you'll never reach their status. Honestly, I know it's cliche and your mom and dad tell you this all the time, but don't give a crap what people think. You hang out with who you hang out with because you have fun when you're with them. If you cared what people think, you'd have to hate everyone. Rumors go around like crazy. I found out today I'm a closet homo. Don't ask me why.
First day, deep voice. Walk slowly. Every other freshman will be walking fast. Walk slowly gaze around. Deep voice. Walk into class right at the bell. Smile or look serious, but don't be a nervous *****. Look confident but friendly. Sit next to the hot girls and ask their names. As long as you look like a normal person, they won't have a ***** shield because they don't know you. You probably won't talk to them after about a month when they realize you're lower than them, but have fun while it lasts. Or maybe they become part of your social proof. Everything is new! Create a new you. I'm a Senior now. I started reading this site when I was a Freshman. I think before I actually went into High School. I have tons of acquitances now (probably 100 out of the 300 students in my grade), but only about 5-10 people I hang out with on the weekend regularly. At first I was completely pissed. I thought damn, I was confident where are all my friends. Realize that most people are losers that don't want to hang out on the weekend. Those that do want to hang out are doing drugs. Besides that, it's all about you man. You can live off cheap moments of fame that don't feel good, or you can kick with the 5 average joes that make you look forward to school every day.
As for girlfriends, I can't help you. I've only had one, and she was handed to me. I'm sure this **** works, but you just got to keep working at it. Don't worry too much, because most guys are going to be virgins like I am still. Like 85% of the guys in my grade are probably virgins, while 60% of the girls in my grade are as well. Live it up. Freshman and Senior year are the easiest. Don't let your grades slip freshman year, it's the easiest way to boast your GPA.