Dress: comfort is king. You're going to want to move and dance, so make sure you're comfortable. Also, try and sneak in some stuff into your outfit that can be an ice breaker. My buddy has a hug dealer shirt he likes, and I'm geeky so I like throwing in some stuff from fandoms I'm into. This will make you more approachable, and people will be more open to being approached. 

Be chill: intentions and vibes are really easy to see on a newbie at a show. If someone is there to hit on/hook up with people, you can tell. If someone is feeling themselves and having a good time, that'll be obvious too. Bring positive energy and just have fun, then people can tell and will want to join your fun.

Don't take drugs that aren't tested: in the heat of the moment, it's easy to want to impress new friends and get the "full experience." Drugs are their own thing to learn to navigate, and there is plenty of time down the road for that. Some people in the scene are irresponsible and don't test their stuff, so you may even know what you're being handed. Much easier to deal with this stuff down the road in a group that is responsible.

Relax: ravers are the most chill and accepting of any music fan group I've known. So first off, you're the one paying the most attention to you. It's easy to feel like eyes are on you and then feel embarrassed about dancing or letting loose. I promise, no one is watching (or if they are, they aren't judging). Just let loose! Dance, headbang, talk to some people. Just do wants going to make you enjoy the show. 

Resilience: ok, this one took a while for me, but I think it's worth talking about so that you can build that resilience. Not everyone you're trying to talk to is going to vibe with you. Sometimes you'll walk up to compliment someone, and they'll give you a look and just walk away. Now a younger me would get self conscious and worry I'd done something wrong, and that would have led to a downward spiral. Instead, just accept that you were being your authentic self, and they didn't vibe with it. There is nothing wrong with that, and it doesn't mean anything is wrong with you. Just brush it off and keep having fun!

For real though, do even a basic search on this subject and there are a tons of posts and advice. This is lazy and aggravating for regular members of the sub.