As Christmas markets are now decorating our towns and cities alongside them you'll occasionally find the odd ride or two which make great photographic subjects after the sun has set.
When it comes to equipment, a wide-angle lens will mean you can capture shots of rides and surrounding details but do consider taking a zoom as it'll help you focus on people riding the rides, food, prizes and other items found at fairs. Your tripod is the second most important bit of kit you'll take with you as when slow shutter speeds are in use working hand-held is hard work. A remote shutter release will help eliminate the risk of blur caused by camera movement and don't forget to wrap up warm!
If you want to shoot general wide shots of the fair then head out just as the lights are coming on when there's still a touch of colour in the sky. That way you'll be able to get the lights, stalls and other foreground interest of the fair set against a deep blue sky. Leave the flash at home though as it can kill the atmosphere you're trying to create.
For more abstract images, wait until the sky's a little darker and turn the rides into streams of light patterns. Look for rides that spin quickly or are bursting with colour as these tend to produce the better results. To do this simply have a play around with slow shutter speeds. Better still, if your camera has it, use the Bulb setting as exposures above and beyond thirty seconds will really blur the movement of the ride and also help remove anyone who happens to be walking through your shot. Just make sure auto ISO is off and that you're using the lowest setting you have. You'll also need to manually focus as auto focus will be searching around in the dark for quite a while then simply use a small aperture to get the maximum depth of field to compensate for any inaccuracies using manual focus may throw your way.
Do take the time to watch the rides to see which angle will give you the best image and do check there's nothing in the foreground that'll spoil your shot. It's also worth keeping an eye on your camera's histogram to check the exposure and consider shooting in RAW so you have the option to tweak the white balance etc. once back home.