True fact: Different dick sizes require different ****ing styles. What this means is that if you've grown say an inch in length or .5 in girth, there's a good chance you'll need to modify your approach to intercourse.
A guy who's 5.5-6 x 4-4.5 can get away with quick insertion and full on pelvis to pelvis "clap" ****ing without much or any pussy prep. His partner may or may not enjoy this approach, but it's not that big of a deal either way. The average pussy can handle that kind of action from the average dick. Ramming it in to the hilt right away, long, full thrusts that smack pubic bone to pubic bone, fast and hard from the get-go, perhaps even going in "dry", pounding, hammering, etc--these are common approaches to ****ing with an average or smaller sized dick. It works (or seems to work) for a lot of guys, and a lot of women seem to enjoy it. So great--if your current dimensions are 6 or less in length and less than 5" in girth, and the above approach is working for you, no worries--carry on!
However, the average pussy cannot handle that kind of action from a bigger than average dick, particularly without skill and adequate pussy prep! There are a lot of reports of guys who are "getting too big" for their partners and suddenly having problems with intercourse. There is even a current thread on the subject. There are also posts from guys with larger than average starting stats who, for whatever reasons, **** like they don't have a big dick, and the results are not good! (It should be noted that many experienced women prefer average or smaller sized dicks precisely because they enjoy this kind of ****ing, and a big dick doing the above can cause real physical damage to a vagina.)
Pussies are incredibly accommodating and resilient places. Very, very, very few guys are actually "too big" for the average pussy. However, If you are bigger than average in either dimension (and particularly both!) you will need to spend some real quality time on pussy prep. You will also need to take a slower, gentler approach to penetration, at least at the outset. You will need to pay more attention to your partner's responses and be ready and willing to slow down or even stop at the drop of a dime. You will need to "sound the depths" to find out if you will bottom out--and if you do bottom out, you'll need to note where that point is and have the control not to thrust to that point: nothing throws cold water on a hot and heavy session quicker than banging up against the cervix. You'll also need to know what positions allow for shallower penetration so you can adjust if need be.
There are also a lot of guys who are probably on the cusp of big, for whom these tips will come in handy, but who also might be able to get away with the "average ****ing style" mentioned above with some women, some of the time.
So here are some basic tips and suggestions for guys with bigger-than-average dicks:
1: Think Big! If you have a 7"x5" dick or above, you need to start thinking of yourself as having a big dick. It is factually and physically true, no matter what your self-perception may be. I'm not telling you to get over any lingering size insecurities or desire to get even bigger that you might have. I'm saying that in a separate part of your brain (the rational part) you should recognize that pussies will need to adjust to you, because most penises are not as big as yours! Even if she's been with much bigger dudes in the past, this still holds true. The pussy will need to adapt. Even with a regular partner who is used to your size, the pussy will need to adapt somewhat to accommodate a big dick! Know this, and act accordingly.
2: Pussy prep: You MUST prep the pussy! If you don't already know how to eat pussy like a champ and enjoy it, now is the time to learn. If you are one of those unfortunate souls who doesn't enjoy eating pussy, train yourself to think of it as necessary preparation for getting your big dick in that tight little pussy, and take pride in good craftsmanship. A couple of pussy eating factors specific to big dick pussy prep: (a) use lots of saliva and use your tongue to work it up into the vagina. Slobber all over the pussy in addition to whatever else you are doing. I know it sounds gross, but you are doing pussy prep here, and good clean sex is all about swapping body fluids--and it's only spit; (b) If you bring her to orgasm with your mouth and/or fingers before intercourse, be aware that many vaginas tighten up after orgasm, sometimes dramatically--so you may not be able to just shove it in even at this point (even if she wants you to, which she probably will!)
3: Sounding the depths: There is part of a paragraph in Give Her the Big O that describes the best way to begin intercourse with a big dick. Here is the relevant passage:
When she is begging for insertion, only put the head in very slowly. Then take it out and then put it in again. Only the head. Do this for 3-4 times very slowly. Then put it in about 1 inch more and then out all the way. Do this for 3-4 times very slowly. You MUST resist the urge to bang this gal hard even though she will be begging you to at this point. Then go in 1 inch deeper and out all the way 3-4 times again. Now do this, and inch at a time untill you are balls deep in this girl.
This should be your default approach to insertion, but with one important caveat: you may or not be able to get balls deep. Instead, you are testing the depth of the vagina to see if you hit the cervix. At the same time, you are still doing pussy prep in that you are allowing the vagina to get used to your girth. You are going in slowly, increasing her arousal by teasing, while also letting the pussy stretch and adjust to your size. This is win/win. (If you haven't done so, I also recommend reading the entire thread--it's a great approach that can work for all sizes. Big dicked dudes just need to figure out the right position and/or slide past the cervix to the CDS, which can easily and naturally be done by adapting VVC's method.) Also, do this only after having pre-prepped the pussy by combining lots of your saliva with her love juices.*
*If you just need to have a quickie, at least spit on your dick and smear some on the pussy, and do #3 extra slow. She'll need a little extra time to lube up. I'm sorry to drop this bomb, but true quickies start to become as rare as toothless deepthroat blowjobs and anal sex when you have a big dick. Just goes with the territory.
4: Pussies, like dicks, are different shapes as well as different sizes. The fit of a given penis with a given vagina will vary, not just in terms of overall sizes, but in terms of the combination of shapes as well. So experiment with different positions to find out what works well with specific combos. If you bottom out in some positions, try and find a position that allows you to slap balls without hitting the cervix. In many positions this can be accomplished by her bringing her legs closer together. You can also adjust your pelvis so you are not pushing in all what way but still touching pubic bones--in other words, try not doing the final pelvic thrust at the end of a stroke. This will vary depending on your shape and hers. Also, even if you aren't bottoming out in missionary, there's a good chance you can or will bottom out in more wide open positions. If she's ankles to ears you will more often than not hit cervix with seven inches. So again, "sound the depths." If you go very slowly and gently, it won't be a show stopper if you touch it, but you'll both feel it. She might have a slightly nervous or frightened look, because she's very vulnerable in this position, and you can really hurt her if you're not careful. So ease back and then push to just before that point. Now you can "hammer" in a controlled manner, making sure that you do not pass that point just before the cervix that you marked out before. Your pleasure here comes from being an expert cocksman, not from just banging away mindlessly. Pride of craftsmanship.
5: Remember that just having a large cock inside her (particularly a girthy one) can bring a woman great joy. So you don't need to necessarily thrust all the time. Try just pausing at various levels of insertion. And when you're as deep as you can go, just hold it there and let her savor being filled. Stirring instead of thrusting is a great option as well. Also, let her "ride" you. When she's on top, pay attention to how she moves. She's learning how to get the most out of your dick. Then, when it's your turn to be active, mimic the kinds of motions she made. There's a good chance that these motions will be counter intuitive, but by learning what parts of the pussy she likes having hit, and hitting them, you'll be increasing both of your pleasure.
Hope this helps. Have fun, and good luck!