Wash it with anhydrous acetone to rid it of as many impurities and adulterants as posssible, then use that much purer yield of cocaine/levamisole to cook into new rocks. $0.02. Not much you can do to potentiate such a short-lived drug like cocaine.
The first times you get a good hit of nice base you may get a hit equivalent to a decent IV shot... Bell-ringer, euphoria sticking you to a chair. But it's got nothing on IV coke. IV heroin is... different, but I say equally euphoric, or hard to compare. It is a hell of a rush.
How to enhance the effects of crack? Wash it with acetone, ether, and water. Make sure you have no tolerance. Get a bit of alcohol in your system, for the biosynthesis of cocaethylene. Take as bit a hit as you can, hold it in for quite a while, and repeat with a huge bowl. If the first rush doesn't get you (stretch for a lungful, and tip your pipe down and sideways so it doesn't all melt down - also first try try to vaporize it, until it melts - then torch the shit out of it), the second hit will.