If you really want to please a woman, learn about her hidden anatomy. Read, The Clitoral Truth by Rebecca Chalker which details the FULL anatomy of a woman's sexual system which is usually omitted from medical literature.
From "The Clitoral Truth" (and a link to a very detailed blog with photos to understand further. http://blog.museumofsex.com/the-internal-clitoris)
If you were to remove the top layer of skin and visible structures of the clitoris, it would reveal numerous hidden structures, which Mary Jane Sherfey referred to as the "powerhouse of orgasm." These structures include erectile tissue, glands, muscles, blood vessels, and nerves. In both the clitoris and the penis, there are two types of erectile tissue: body of caverns (corpus cavernosum) and spongy body (corpus spongiosum), which fill with blood during sexual response, causing an erection.
The clitoral shaft is attached to the glans, just underneath the surface of the skin. The shaft is a round fibrous segment of spongy erectile tissue, and like the glans, it is very sensitive. If you roll your finger back and forth just above the glans during sexual response, you should be able to feel a hard ridge about one-half to one inch long, and about the diameter of a soda straw, and rises toward the pubic mound for a short distance, then bends sharply and divides, forming two slender legs or crura (Latin for "legs"), which are also composed of spongy tissue. The legs of the clitoris flare out somewhat like the wishbone of a chicken.Underneath the inner lips are twin bulbs of cavernous erectile tissue. During sexual response these structures fill with blood, which then becomes trapped in their cryptic spaces, causing erection.In both women and men, the urethra (the tube through which we urinate), is surrounded by a ring of spongy erectile tissue that is identical to the type of erectile tissue, corpus spongiosum, that surrounds the penis. In women, the urethra is about two inches long, and runs from the bladder to the urethral opening just above the opening to the vagina. "In nearly all of the modern anatomy books that we looked at, the erectile tissue surrounding the urethra was missing," Carol Downer says. "Although it is clearly analogous to the spongy tissue which surrounds the urethra in men, it hasn't been considered a part of the clitoris for several hundred years. Since it had no name in women, we decided to name it the urethral sponge."The urethral sponge is a very significant part of the clitoral system. Embedded in its spongy erectile tissue are up to thirty or more tiny prostatic-like glands that produce an alkaline fluid similar in its constitution to the male prostatic fluid. Two of the largest, called Skene's glands, are near the urethral opening, where the urine comes out, but numerous others are buried in the spongy tissue surrounding the urethra. All of these glands together are referred to as paraurethral glands, meaning "around the urethra," and they are the source of female ejaculation. Normally, the sponge is collapsed and is difficult to feel, but during sexual response, if you or your partner puts a finger in your vagina and presses toward the pubic mound, you can feel a rough nugget about the length of the first one or two finger joints; that is the urethral sponge. When the sponge is filled with blood, i.e., erect, many women find that it is extremely sensitive to stroking, thrusting, or vibration inside of the vagina. The "G spot" is located on the part of the urethral sponge that can be felt through the vaginal wall.