It's a very good idea to thoroughly wash the penis and the surrounding areas before starting any fellatio. A warm, wet washcloth or towel is usually sufficient - and also feels great to him. The taste and smell of a man can vary depending on the time of day, his diet, personal hygiene and level of arousal. It's normal to see a little pre-cum appear at the tip just as he's getting all the way hard, but if a burst spurts out, he's blown his load early and your job is over before it's begun. While you don't have much control over his orgasm, there are many things you can do to enhance the experience.