Getting comfortable receiving oral

definitely no pro at giving oral, but I would love to do it for my wife. I have given her oral a few times. I got the feeling a time or so it was doing something for her. She recently told me after I did that she thinks it is gross and really doesn’t do anything for her. I respect her feelings but would love to do it for her and get to the point where she really likes it. Obviously I need to discuss it with her. I’m looking for advice on how to proceed with discussion or in any thing related to this.