Ah the long hair, one of my more favorite subjects to discuss.
I've had long hair for about 3 years now, or so. It's curly/wavy and is below shoulder length, but fairly above chest length.
"Scientists view long hair as playing a large part in any animal species' natural selection, since hair length is frequently a sign of health."
Long hair can mean many different things contingent to it's length. I'll tell you right now - Long hair will give you the most sporadic results with women you'll probably ever see. Some women will love it, some or most will probably hate it. It all depends on their preference. Long hair on men continues to possess a great deal of stereotypes. Most believe long hair on men will typically look unkempt and/or greasy.
You must know how to care for it, if you want it. I have women ask me all the time what shampoo/conditioner I use because of it's condition. If you are able to keep it looking nice, you can catch some really nice comments, and some girls will even be jealous

. I use my long hair to my advantage and it's congruent to my personality - I am a lead vocalist of a band. Women have always given me mixed signals but I realized since I love my hair, why would I want to mate with ones who don't like it? Other than using it as a personality signifier I also use it for selection. I'd rather mate with those who like or don't care for my long hair, so it works in both ways.
Sure there are exceptions, but it's good to have a style that fits your personality for ultimate congruency. If you have chest length hair, people and women more so aren't going to perceive you as a business man making a six-figure salary, you know? I personally see long hair as a sign of individuality and use it as I see it. Say I was wearing the exact same clothing as 3 other guys. My hair would obviously stand out between them because it's out of the ordinary, which is also like a natural peacock.

It actually works very nicely as a peacock tool since if you think about it, guys are generally looked at as having short hair - it's universal. So if you can still show signs to create attraction while still having long hair, that can say that you can easily deal with the social pressure of having long hair, making you even more socially dominant.
Take a word from Mystery for example:
Say there's a group of 4 girls. If you don't have a specific identity, all 4 of them could easily say no and reject you. But if you have a specific identity and are really congruent with it, 3 of them can reject you, but 1 will say fuck yes!
Hair is a very tricky subject. One HB10 might absolutely love long long hair, and another HB10 might absolutely hate it and think it's absolutely disgusting, it's all preference really.