Cocaine is the best and the worst drug in the world. I have a love-hate relationship with it. Cocaine produces an indescribable sensation. The weight of the world is taken off your shoulders, you're happy in a bizarre and jumpy way, and you can't shut up (in my case). Your nose becomes numb, as does your throat. You feel as if you have a bubble in the back of your throat. I enjoy drinking cold iced tea when coked up. One of the best parts of cocaine is taking some on your finger and rubbing it on your gums and tongue. This will cause your entire mouth to get numb, and I suggest chewing gum because it's such a good feeling. Putting some coke on the end of a cigarette and taking a few pulls also feels nice.
However, all good things must come to an end. Some people crash worse than others; I have only had one really, really bad crash in my experience. This brought on a feeling of hopelessness and an emptiness in the pit of my stomach. When and IF you crash, seeking more coke will help temporarily, but your best bet is to just call it a night and try to fall asleep in a peaceful atmosphere.
You also have to be careful who you get it from (make sure it is a reliable dealer). It is almost impossible to find 100% pure cocaine nowadays, but some dealers will really give you complete bullshit and you will have wasted your money.
If you have an addictive or unstable personality, DON'T DO IT. I have someone in my life who has been battling cocaine addiction for years now. Rehab has not been able to help. The hardest thing about dealing with an addict is that NO ONE can help them unless they want the help. This person has spent thousands of dollars on coke binges. Cocaine can alter your priorities if you aren't smart about it. Don't blow all your money on it!
Taking a xanax or similar anti-anxiety medication alleviates the "crash" when coming down from the cocaine.
Taking a warm shower as you're coming down also helps immensely.