I am writing this as I have heard so often that so many men (A) have no interest in this activity, even though they can't wait to get their dick sucked, or (B) they don't mind giving it a try, but often cause more frustration than pleasure. The former have no idea what they are missing, and to the latter. . .read on.
What I think may be the most difficult concept to wrap their brain around for most men is that the act really all starts in the head, and not between the legs. Those that just spread the legs and dive in may have some success, but will never realize the same heights of those that understand this simple concept. And the women have to realize this as well. I have always thought it is important for them to be comfortable, relaxed, and have a clear mind.
Another key element of success is for the man to take his time. There is no hurry. Your lady must warm to your voice, your touch, your tongue and your lips. The more patient you are the more intense her orgasm will be.
I'd start at the very beginning. Taking her clothes off. One piece at a time.
Talking to her as you go. Making her feel comfortable about her body and letting her feel comfortable with your touch. After you take the shirt and bra off, maybe spend a couple minutes right then and there playing with her nipples a bit. Feeling them, kissing them, some light pinching and nibbling. Just a bit, to get it all started. Undo her pants and pull them down then off. Let her stand there a minute. Maybe feeling her through her panties. You running your hands around them. Sometimes I even leave them on for a bit, and other times not.
She's naked now, or almost, and time to lay her down on the bed, the sofa, the kitchen table, wherever. Lay her flat on her back then snuggle close up beside her. Your face next to hers. Kiss her on her lips, brushing yours up against hers. Let her feel your tongue slip in her mouth, and swirl around hers. Your lips up and down her neck, then across her shoulders. The sheer power of a simple kiss should never be underestimated.