When we think of good sex, we probably think of multiple positions and techniques. What is strange is that we do not apply this same thinking to other kinds of sex. In fact, all other types of sex have many different positions. There are some positions that can make oral sex so much more exciting and enjoyable.
One of the most common moves is the 69, and most people are familiar with it, so you can have some fun by alternating from being on the top to being on the bottom. Secondly, by placing a cushion under her hips, you can angle them upwards to make it easier to access her clitoris. If she likes this feeling, she can move the pillow further up (To the small of her back), and this will angle her clitoris downwards, giving her different stimulation.
One of the fun oral sex positions is for her to be on top. You will want to reverse the previous sex technique and have the pillow under your hips. Experiment with some angles as some will allow her to go deeper than others. With her on top, she also has more control over her pleasure and can grind her hips against your mouth and tongue. From this position, it is easy to locate her perineum and anus if she likes those kinds of stimulation too. As she gets more excited, she can increase the thrill by raising to sitting position (Make sure she takes some weight off her legs or agrees on the way to signal if it is uncomfortable). This elevated position allows her to really grind her hips and bring herself more quickly to orgasm.
If the straddle is too much for you, then move her to a standing position. This has some benefits and disadvantages. The benefit is that this oral sex position gives you easy access to both the clitoris and even the G-spot. The big problem is that your neck muscles are relatively weak, so it can be tough for her to get the right amount of pressure to have an intense orgasm. Therefore what I recommend is to get her to lean back against the wall. This has two advantages: if allows you to lean into her, using stronger muscles to lock your head and it allows you more access to her erogenous zones.
Of course, no oral sex positions guide would be complete without doggy-style. This can be a great addition to oral sex as it gives the guy so many options about what to stimulate. By mixing oral sex and perineum/ anal play, you can give her a range of great feeling.
Like other kinds of sex play, variation and constant surprise are the most important things. These sex techniques are great for helping women to have their first orgasm or giving her yet another one. Make sure that you surprise her as much as possible, changing the angles, positions, strength, and frequency all the time. Once you find one that brings her to orgasm, stick to it and watch her go wild.