Photographing at night can be one of the most rewarding genera of photography. It can also be one of the most challenging. The inability to see is the greatest problem, and knowing your gear well enough that you can set up and operate by feel will go along way to making your trip far more productive. I have been using my canon gear long enough that I can change lenses and operate the camera by feel and not need a flashlight to see by. Careful packing will also help, the less time you spend digging in a bag looking for a memory card, the more time you can focus on shooting. Before shooting at night, I completely empty my bag, and put everything where it belongs, then when I get on site, I do not need a flash light, just reach in the bag and grab what you need by feel. If you have ever worked in a darkroom, this will all seem very familiar.
Planning your shoot can make the whole evening easier as well. I scout locations during the day, taking note on where foreground and background elements are in relation to each other. I use a few apps during the planning. Dark Sky finder (http://www.jshine.net/astronomy/dark_sky/) will help you find areas that have little light pollution. Find an area on the map with little light pollution, then head out and scout locations, looking for anything that will look good with the star field in the background.
I use stellurium (http://www.stellarium.org/) to find where and when astronomical objects will be within the area that I want to shoot.
Once you get to your location, and have your cameras and tripod set up, the darkness presents yet another challenge. You will usually find that looking through the viewfinder it will be too dark to see what you are shooting at and too dark to focus. If you happen to have a light off in the distance, you can usually have the auto focus on the camera work on the light, just focus and then turn the auto focus off and be careful to not bump the focus ring. If you have no lights you can try using a flashlight to illuminate some trees off in the distance, but I have had a hard time getting infinity focus with this technique. Usually what I do, is set the lens to infinity, set the camera to the highest possible ISO (on my 5d it is 3600) and take a picture. I am using the highest possible ISO to have the shortest possible time per picture to check focus. I will take a picture then chimp the results and refocus as necessary, until I have perfect focus. It will usually take 5-6 images for me to get focus right on. Since I cannot see exactly what I am framing up, I will also use the focus frames to check what exactly is in the frame and fine tune the framing of the camera. Once I have achieved focus and the precise framing, I will do one last test shot, chimp it check focus and framing of the subject, then I will reduce the ISO to a useable value (usually 800-1600) and take my picture. I use a wide aperture wide lens like a 24/1.4 or a 14/2.8, shooting a wide lens will allow you to shoot a much lower ISO giving you a cleaner image. I find that often, I am shooting at ISO800, f/2.8 for 30-45 seconds. I have found that if I am shooting at 14mm, I can shoot for 45 seconds with little blur from the stars.
You will also find that photographing the night sky can be very cold. The skys are clearest when the temperature and humidity are lowest, so getting out the in the winter to shoot the stars is the best time. Keep your batteries in your pockets, to keep them warm, and use hand warmers wrapped around your lenses to keep dew from condensing on your front element.
Good Luck 🙂 I’d Love to hear what your tips and experiences are.