You can't do a line of coke. It's impossible.
Anytime you see somebody snorting a line of anything that person is a clown. You're supposed to fold a dollar bill in half the long way. Then you cut a straw to about the length of your pinky. After you've cut the cocaine in half (baking soda works but there's other things you can cut coke with) then you sniff half of a half of a line in one nostril and half of a half of a line in the other nostril.
Powder cocaine doesn't hit you like crack. It takes a while before it starts to effect you, like wine. By the end of the night you'll be sitting there with your mouth wide open and your legs will be shaking.
As far as I can tell, powder coke and crack are polar opposites. As much powder as I've done in my lifetime, I've never had the urge to rob somebody or sell my body to get more powder. I've also sniffed heroin in my lifetime but that's a monster, there's ways of gradually withdrawing from heroin but it's impossible to quit cold turkey.
I'd like to say that powder cocaine should be legal, but as soon as you cook it into crack it becomes something totally different.
My recommendation is to stick with weed and alcohol and if you can find some powder cocaine, give it a try. But stay away from crack and heroin.