After ejaculation, your sexual system relaxes. It takes minimum half an hour to get aroused again. There is a technique called -edging-. with this technique you can enhance pleasure as will as you train your brain to delay ejacuation. Google edging to learn the details.
Hi masturbating is healthy but don't expect the same amount each time you do it , the body has to have time to produce more sperm , its up to you how many times you do it but don't expect a better climax as the first one , you will come to no harm tasting your sperm at all , pre-ejaculate is clear its the body's lube comes when you are excited , its normal , Take care , Enjoy your Teens ,