One of items I always take with me to do on site research and especially to any library is a digital camera (assuming cameras are allowed, which sometimes they are not). The photo above is digital image taken with my hand-held camera of a random roll of microfilm projected on an ordinary microfilm reader in the Mesa Regional Family History Center. The hotspot (bright light) on the image is caused by the projector light on the microfilm reader. Other than holding the camera steady against the top of the microfilm reader, the picture was taken entirely using the light from the projector bulb.
By loading the image into my computer using Google's free program Picasa, I can easily zoom in on the smallest detail of the image. Although the copy of the image above is of lower quality than the original taken with my camera and loaded into my computer, if you click on the image, you will see that there is more than adequate detail to read any portion of the page. You can get even greater quality by using a simple tripod or other method of stabilizing the camera. This method is much faster and easier than removing the film and taking it to a microfilm printer to get a copy of the page.
I recommend a camera with a ten megapixel image, which is the norm for moderately priced cameras these days. Having a photograph of the microfilm image to take back home and study gives you the ability to gather much more information for each trip to the facility.
There is no "trick" to taking these photos other than a steady hand or a tripod. It helps to have a single lens reflex (SLR) camera so that you don't accidentally crop the image in a way to lose information. If you use a more common range finder type camera (one with a separate viewfinder) you may wish to check the image in the camera's preview before moving on to the next picture.