I thought that it would taste disgusting the first time i tried it but guess what, i loved it and it's gotten better every time since. And you will know when she orgasms because the taste of her will actually change as she cums, but the taste of a healthy woman is great. All guys should be prepared to give chicks oral even if the chick doesn't reciprocate the act because it will make her feel extremely sexy and you should find you enjoy doing it for her. And i also agree with ZMAW hold her hand it will make you feel a deeper connection to her and you can tell more easily just what is working for her because when you hit the right spot you will find her grabbing your hand like she wants to break it off
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so don't worry about the taste because there is nothing wrong with it just enjoy it and the best rule to follow in regards to any sexual activity is just go with the flow.