Bliss,
A good question, and you have already received good answers. There are other threads, but this has to be just about the most important issues we have to face.
But in my view, it needs at least a two stage approach. "Putting it in", if you have a very big glans, is one stage; then, when she begins to be accustomed to your thickness, a gradual increase of depth is another.
I agree that the 'woman on top' position gives her control; but I can vouch for the fact that she can still hurt herself -- and hurt you -- if she is uncontrolled, if she pushes down too far, or if she loses her balance. Some more average guys can use their whole length in that position so that she is sitting right down on them ... no way will that be possible for you to start with, if ever. The vagina tends to shorten in that position ... my experience bears this out.
I would concentrate at least to start with just on initial penetration. The head only. No doubt as any other well hung guy would tell you, you need lots of patient foreplay, lots of lube, and to be gentle yet firm. After she is used to that you can begin to encourage her to take more length -- that gradual process of adjustment can be the sexiest thing in itself IMHO. It's best I think always to give her a bit less than she wants at any stage. Keep her wanting more, which, after all, you are the guy who is well equipped to give her ....