Women often (with exceptions, of course) have a more difficult time throating large partners as the esophagus diameter is a limiting factor. While somewhat elastic, it can be painful to force something down that simply doesn't fit. Expect your throat to feel it afterwards, especially if he's thick.
Here are a few things that have helped me:
- Be well hydrated. It helps you make more saliva and esophageal lubricant (mucous)
- Have an empty stomach. Even if you think you have your gag reflex under control, accidents can happen.
- Straighten, or match, the bend. Be sure that your neck geometry matches the shape of his cock. If he's straight, tilt your head back so he has a straight shot. If he's curved up/down/left/right, align your body so it will not try to bend him a different direction. I love 69ing a super hung guy when he has an upward curve. It's like it was made to be throated!
- Use your tongue. It's a very powerful muscle, and with training can do wondrous things. When relaxed, the back of it is thick and takes up a huge percentage of your throat, so learning to flatten it (stick your tongue out...far!) is super important.
- Use your tongue. Think of it as a conveyor belt that can draw his cock in with it. When he's at the back of your mouth, reach out as far as you can with your tongue and pull him in with it. Takes practice.
- Use your tongue. Make his balls your tongue target. Think of how incredibly turned on he'll be when you get him all the way down and can savor his balls with the tip of your tongue. It's one of those motivating things that I aim for.
- Don't just choke him down. Think of your throat as a wonderful extension of your vagina. Make love to him with it. Fuck him with it. Try to orgasm from the feeling of bringing him to orgasm with it. Don't just bask in the triumph of getting it down then go back to just the head, unless you want to work the technique, then back off and give your throat break until he's ready to come and then swallow him again for the main event.
- If you don't have a dildo to practice on, get one, or several. Longer and thinner is good for basic training, then progress to something thicker to understand the difference in techniques necessary. Of course, if your man wants to play the part of the dildo and be patient and understanding (I would be!), all the better. Don't get discouraged; it's not something many have the dedication to master, which is what makes it special.
Above all else - Have fun!