You can just straight tell him that you would really like him to give you oral. Its also important that you lead him during it a little to your sweet-spots, so he can make you cum.

Once he learned that you can cum from him giving oral, he will probably put more effort into it, too. Also, try to be as clean as possible.

Your taste is not that important, most guys have their "ways" to work around bad taste and do not really mind. So do not worry too much about that but you can still ask if you taste bad if he acts kind of flaky around the subject.

You can want to learn communicating all you want but the fun thing is, communication comes from talking and listening a lot so do not avoid topics that seem a bit embaressing. Embrace them and with the right person, it will be rewarded.