What kind of camera do you have?
Been thinking of getting one
Quality and capabilities change often, so what someone bought 4+ months ago might not be as capable as newer versions/brands.
There are many being marketed under different names, even though they are the same product. That makes a difference in features and price.
Get one with GPS. The one I have included a GPS mount/base -- an option if you just buy the camera and later want GPS.
GPS will record not just location, but also speed. That's very useful if you get pulled over for speeding and are sure you weren't speeding. I had a friend who didn't get GPS with his camera. He was ticketed while being clocked in a 35 zone, but he was pulled over just past a 25 MPH sign. He was doing 35 in the 35 zone. Had he been able to show his speed and location, he'd have beaten the ticket.
I also recommend the highest resolution you can find/afford. Nothing worse than trying to use a grainy video as evidence.
I've found the worst problem with cheap cameras (DVRs) is battery time. I have mine set to power off a certain number of minutes after the engine is turned off. I'm lucky if I get 10 seconds. That's been the case with 3 other brands. I guess as small as these are, the battery capacity can't be very high.
I've considered moving the power wire to a fuse that's always on versus the radio or cigarette lighter. I can't see that small of a load draining the car battery, but I'm not 100% sure.