Kill the Flash
Please, for the love of good looking photos, turn off the flash. Flashes on most consumer cameras are nearly useless. Unless you absolutely can't see anything in the photo without the flash, you're better off without; it's that simple. Photos of people and things almost always look better without the flash, and beer definitely falls in that category. Flash light reflects off the glass, and washes out the photo. Improve the ambient lighting if you need to, or find another location to shoot before you turn the flash on.

Depth of Field
One theme you'll notice in my photos is that I like to shoot with a shallow depth of field, meaning very little in the photo is in focus, other than the subject. I do this because things and people generally look better when they are isolated from the background.

So how do you shoot with a shallow depth of field? If your camera allows you to set the aperture, great! Choosing a wide aperture(lower number) will give you a shallower depth of field, and it also lets in more light, which is usually a bonus when shooting indoors. If your camera doesn't allow you to control the aperture, choose the portrait mode, and the camera should do that automatically.


Focus
Now that we're shooting with a shallower depth of field, we need to talk about focus. When you shoot with a wide aperture, less is in focus, so you need to make damn sure that your subject is in focus. Photographing beer can be tricky in this sense because images refract through the beer, and your camera's autofocus may struggle to focus on what you intended. It's always a balancing act between focusing on the glass, or focusing on the image refracted in the glass.

Lighting
I find that beer looks best when there is even light through the beer to empathize the color, but not too much light so that the rest of the photo is under exposed. Also, direct sunlight tends to wash out the photo. Basically, don't shine a flashlight through the beer or hold the beer up to a light, and don't try to take photos of beer in direct sunlight. You can get great photos indoors, but you need to turn on all your lights, and definitely don't use the flash.


Composition
If you can keep your beer out of the dead-center of the photo, it's usually for the best. Photos almost always tend to be more interesting when the subject isn't dead center. One of the basic composition concepts in photography is called the rule of thirds. Imagine if your photo had two vertical lines dividing it into three equal sections. The rule of thirds is that you should compose your photo with the subject along one of those lines rather than in the center.

Camera
I do have a DSLR, and I love it. It takes some fantastic photos. With that said, you don't need an expensive camera to take great photos, nor does an expensive camera lead to great photos. I shot this photo and this photo with my iPhone, which I can promise you is no where near as good as a typical point-and-shoot camera. Sure they aren't as sharp and crisp as a DSLR shot, but they still capture the eye.

So get creative, and spend a little time taking better photos of your beer. The awesome thing about digital photography is it doesn't hurt to practice as much as you want. Get out there, take some pictures, evaluate which photos you liked, and what you liked about them. Then wash, rinse, and repeat!