So you want to install a dash cam:
There's a lot of different models out there that have a wide variety of options. Personally, I am a huge fan of my Mobius, but there are others out there. This post will go over what I did in really super-general terms that should more-or-less apply to any car and any dash cam, but I'll post exactly what I used to set things up the way I like.
Parts needed:
-Dash cam (duh)
-Dash cam mounting hardware (suction cup, adhesive, etc.)
-Multimeter
-Add-a-circuit (the type that fits in a fuse slot, make sure you get the right size)
-12V to 5V USB converter
-Appropriate length USB cable
-Mounting adhesives/zipties (as needed)
-Tools to remove trim (as needed)
Steps to install:
1. Locate a suitable interior fuse box. Usually there's one somewhere around the drivers' side footwell.
2. Use multimeter to select a fuse that has switched (accessory) power. It should turn on when you turn on your key and turn off when you turn it off.
3. Solder or crimp the power converter to the add-a-circuit, locate a suitable ground point (a bolt/nut on the body of the car is good), and hook up the ground on the converter.
4. Put a 3A fuse in the add-a-circuit for the 12V converter and put the fuse that you located in step 2 in the pass-through slot in the add-a-circuit.
5. Put the add-a-circuit into the fuse slot from step 2.
6. Test the add-a-circuit and converter. I like to plug my phone into the converter to do this: it should charge when you turn the car on or into the accessory position and it should stop charging when you turn the car off.
7. Mount the camera where you'd like it to live. Note: plug the USB cable into the back of the camera when you do this since it can stick out pretty far and interfere with rear-view mirrors or other things. You can also use different a USB cable or a 90-degree adapter to help with this too.
8. Working from the camera back toward the fuse box, start placing your cable. Several notes here: This depends heavily on the type of car and the location of the camera. Level of effort will range from just pushing the cable along the headliner and A-pillar to a full removal of the dashboard and A-pillar to make it look right. Use your creativity, and be sure not to interfere with any airbags or other safety systems. Also be sure to leave a little slack on both ends of the cable so you can move things around if needed.
9. When you reach the fuse box, plug everything in and use your adhesives and zip ties to package everything up out of the way, and control any excess cable you may have.
10. Get involved in a hit and run, have evidence for the resulting police reports and insurance claims.