"Since you happen to really like blow jobs, and you’re not doing it JUST for him, I want to try and help you out. The most important thing I can suggest is that you talk to him about it. Be sure to tell him how much you fucking LOVE giving him head, how you want to experiment with techniques and positions until you find something that works for both of you, so he can enjoy receiving as much as you enjoy giving. Communication is everything when it comes to this kind of thing.
Now. We will get to your mouth in a second, but first a reminder that great oral sex technique starts with great manual sex technique. Amazing blow jobs have as much to do with how you’re using your hands as they have to do with how you’re using your mouth. You may want to brush up on your handjob techniques by checking out this article. Many of the techniques can be utilized to good effect during fellatio as well.
If you can fit the head of his penis in your mouth, then you can do that and just swirl your tongue in circles around the coronal ridge and then up to the tip. You can bob your head really fast or painstakingly slow on the glans. Then, remember to use your hands. Put one hand around his penis and press it firmly against your lips, like in this picture, as well as in the second picture down on this link. More on that in a minute.
There is a lot you can do even if you can’t fit your mouth around his glans – just use your tongue! You can lick every inch of his penis with your tongue wide and flat, as if you were licking an ice cream cone. Another option is to quickly flick the tip of your tongue against his head, coronal ridge, and frenulum. You can make your tongue hard and pointy and circle the ridge under the glans. Many men love it even when you just flatten your tongue and use the widest part of it it to rub against his frenulum.
Whether you can fit his penis in your mouth or not, remember to use lots of lube to make his penis slippery and use your hands extensively. Try some of the techniques you saw in the hand jobs article. A technique I strongly recommend is the gentle twisting stroking method, where one hand goes down and up (with your wrist flexing forward and back) as you use your mouth on his glans. If he’s long enough, you can use both hands at the same time. Place your hands so that the thumb on the bottom hand is right against the pinky of the top hand, and stroke up and down with both hands together. If you use the twisting method, use a loose grip as you twist in opposite directions and keep the stimulation light, with a lot of lube. No pulling his skin!! If he likes ball play, you can use one hand on his balls, or keep your hands on his penis while you lick his balls.
To sum up, I recommend that you focus on your hands, use a lot of lube to keep it wet, and use your tongue instead of your lips/mouth to stimulate his penis. If you can manage it, put your lips around his glans and lightly tease that with your mouth as you go to work on his shaft with your hands.
But I do have one last important tip. If you use lube in the process of giving a blow job, chances are good that you’ll get some in your mouth, so it’s important to find a lube that doesn’t taste too bad to you. Try a few until you find one you like."
See the question and entire answer @ TheSexperts' Lounge