sillysally: Okay, I'll give this a try. I'm not sure that this advice is specific to big guys, though. Haven't had enough to be an expert.
First of all, I'll assume you are a gentleman and we have had plenty of foreplay. When properly warmed up I am pretty wet and don't need much extra lube. This will vary woman to woman.
The next thing to know is that anticipation is everything. Don't just get in there an start banging. In the later stages of foreplay, begin teasing me. Rub you cock around my slit. Do overdue it. Just enough to make me want you more. You might even push the head up against me to the point it just starts to push the lips apart. That first entry is the best part. Give me a few hints of that grand entrance and then pull back. It'll make me want it even more.
When you do finally penetrate me, go slow. Don't just ram it in. Again, this first penetration is a great feeling. Don't cheat me out of it by slamming it in me.
Once we are fucking, give it some variety. Mix in a string of short strokes with one deept one. Spend some time concentrating on the first 1/4 or so of my vagina, then push it in once and remind of of what you've got. Follow that up with some grinding, keep it in deep and grind against my clit. Then you might do some long pumping, butthink like a dancer - move you hips as you go. And don't bang me, make love to me. I'm not a punching bag.
Another word here about the clit. This is my most sensitive part. Find every reason to grind against it, drag across it, etc. If you keep this in mind as you are stroking and keep finding new ways to stimulate me with your cock and pubic bone, you will have a better chance of making me come.
A word about bottoming out. I actually don't mind this, assuming it is done with some care. I do not want you to batter my internal organs. That hurts. However, if you gently poke my cervix and show me that you can reach all the way in, I won't mind.
Finally, mix up the positions, but not too much. Maybe we could take turns choosing positions. I might want some woman on top, you might want a bit of doggy style. It should be give and take. I don't, however, like to play Twister, changing every few seconds. Nor do I like to be flung around like a rag doll. That's just me and others might have a different prefence.
If you can pull of something along these lines, you have a good chance of making me a happy woman. That's my definition of knowing what you are doing. I hope that helps.