the battery and car's negative clamp on terminal (easier and safer using negative side of battery) . Do this with all car doors and hatch closed, lights off, car off, etc. Pull each fusible link (box in front of battery) and note which one drops the current draw. This will tell you what general circuit branch has the issue. From there you can pull specific fuses for that branch circuit to figure out the exact circuit misbehaving.
Note - aftermarket stereo amps can also be a source of excess current draw issues if the amp's on/off relay sticks on when car is off. Another easy thing to check..
