There's a product called a Lenskirt, which is a suction-based large lens hood, it attaches to the glass and eliminates reflections. I've never used one, so can't say yay or nay about it.
I saved an evernote from a website a while ago about this very subject:
* Hold your camera with both hands and keep your arms in close to your body. This will help you keep the camera still for longer exposures.
* If your camera or lens has vibration compensation be sure to turn it on.
* Shoot in Aperture priority mode if using a DSLR. Make sure you have an aperture setting that will get the portion of the object you are shooting in focus. This might be an f2 if you only want an animal’s eyes in focus or an f 4 - 8 if you want the entire scene in focus. Just remember the lower the number the longer the shutter speed is going to be.
* If you are using a point and shoot camera, check to see if you can set it for a low light or museum mode in leu of choosing a low aperture number.
* Get right up to the glass, without touching it.
* Use manual focus if available and if it is not, use the focus lock on your camera to select a focus point. To do this pick a focus point and then press your shutter button half way down. This will focus the image. When the spot you want to be in focus is in focus, gently press the shutter button the rest of the way down.
* Take lots of photos. However, be mindful of other guests and don’t hog up the displays.
Hope this helps
