Dialogue needs three things, CONFLICT, CONFLICT, CONLFICT. If you manage to put these things into each line of character dialogue you do, you will have fast, flowing dialogue. But that is not all, you must also make dialogue SOUND real, "I am Mr. John from down the road around the corner. I am very pleased to meet you." Does not sound real, it sounds like a robot is talking - of course, if a character is from another world or IS a robot, it is good to have them talk like this - but all in all, no normal person would speak this way. "Hi, I'm Mr. John, I live just down there. It's nice meeting you." Sounds more real, but still not real enough. Often 4-5 drafts of each dialogue is needed to finetune it. Also don't say what your character is feeling, show it, make him yell when he is angry, instead of simply saying that he is angry. If you follow these rules, you will quite possibly come out with good character dialogue 95% of the time.