Esencia, there are a list of medical disorders that can cause frequent nosebleeds. If you have any other symptom along with the nosebleed you will want to ask your doctor about them:
Autoimmune Lymphoproliferative Syndrome (symptoms: skin rashes, anemia, bruising, enlarged lymph nodes, enlarged spleen)
Autoimmune Thrombocytopenia (symptoms: purpura, bruising, poor clotting, bleeding gums, skin lesions, nosebleeds, enlarged spleen)
Immune Thrombocytopenic Purpura (symptoms: bleeding, bruising, red dots on skin, nosebleed, bleeding gums, gastrointestinal bleeding)
Thrombocytopenia (symptoms: bruising, bleeding, clotting failure, Petechiae, Purpura, oral bleeding, nosebleeds, gastrointestinal bleeding, enlarged spleen)
Of course it could be nothing more than having a nasal polyp, a weakend blood vessel in the nasal cavity, or chronic sinusitis. And dry air followed by dust and sand not only dries out the nasal cavity but also is abrasive to the nasal wall resulting in nosebleeds.
I was going to ask you if you used "recreational drugs" but since you said this has been happening to you since you were 8 I figured Cocaine usage was out of the question

Also wondering, is the nosebleed one-sided? Because if it is, you could have a deviated septum. The septum divides the nasal cavities and if it is not straight then the air flow is uneven and one side of the septum may dry out, chap and bleed.
As for what to do when you get one, never tilt your head back. I cringe every time I see someone do that on a tv show. Just sit down and lean forward slightly. Keep your head above your heart level. Use your thumb and index finger and pinch the soft portion of your nose (above nostrils). Keep holding until the bleeding stops, don't let go for at least 5 mins. If you are still bleeding, then hold for 10 mins straight. When the bleeding stops don't do anything like bending or blowing your nose because that can start the bleeding again.
And to prevent further nosebleeds keep the lining of your nose moist by applying vaseline inside your nose twice a day. Also use a humidifier (as Clare suggests) at night in the bedroom and if you smoke, best to quit. Smoking dries out the nasal passages and irritates them.
Hope some of this info is helpful and please let us know what the doc says.