Despite what others will tell you, the answer is not expensive hair growth pills or rubbing egg yolks on your hair (eww).
If you want your hair to grow long, you have to cut it. Say whaaaat?
I have two words for you:
On a weekly basis at the salon, I meet girls who have put off getting a haircut for over a year because they are trying to grow out their hair. Do you know what this usually results in? Tons of split ends and gross, scraggly, ugly hair at the bottom. What's the point of having long hair if it looks like it had a fight with a chainsaw?!
Don't be those girls.
Split ends are when your hair has literally begun to split. Left unattended, they will continue to split farther up the hair shaft causing damage and breakage higher up on the lovely locks you've been trying to grow long.
Do yourself a favor and get a haircut or a "trim" or whatever you want to call it (it's a haircut).
Once I've explained this to them, the most common answer I hear is, "Okay, so maybe half an inch, at most?"
Oh honey, you wish. You need to take off ALL the damage. For most people it's maybe two inches. For extreme cases of split end denial, it could be six inches. Only cutting off a little of the damage isn't going to stop it from splitting upwards.
This is where you have to ask what is more important to you.
Do you want long, healthy-looking hair?
Or do you only care about the actual length of your hair, no matter how scraggly, nasty it looks?
At this point most of my clients will pick healthy-looking hair over dry, dead-looking length. When they allow me to take off what is needed, they always say, "Oh yeah, that looks so much better!" "It looks so much healthier." And "It looks so much thicker!"
If you want to grow your hair long, you need to cut it regularly. Every 3-6 months should suffice, depending on how well you treat your hair.
You may need a good few inches taken off the first time. But if you are good and get it cut on a regular basis, you will need MUCH less taken off on your subsequent salon visits.