This writeup covers the method I use to jack up the front and rear of our Impreza TS Wagon. I assume no responsibility for any damage you do to your car or yourself. Familiarize yourself with the proper use of your floor jack and jack stands, and be sure to consult your owners manual for the correct procedure on your car.
* Floor jack
1) First engage the parking brake.
3) Roll the floor jack under the front of the car. The jacking plate is behind the oil pan. Raise the jack.
4) There are notches on each side of the car, just behind the mud flaps. These are used as the jacking points for the small scissors jack which comes with the car. Since you don't want to bend anything in this area, choose a point slightly in front of these notches to place the jack stands.
5) Place both stands under the frame, and lower the jack slowly.
6) Verify that the car is stable on the stands before working under the car. You can leave the jack in place, but never rely on just the jack to support the car. When you're done working on the front of the car, use the front jacking point to raise it back up, and remove the jack stands.
7) The procedure for lifting the rear of the car is similar. Make sure the parking brake is engaged.
8) Block the front wheels.
9) Position the jack under the rear differential as shown, and place a block of wood between the jack and differential. Raise the jack.
10) Locate the notches on the side of the car, below the rear door.
11) For the rear support points, I chose an area just forward of the rear notches. Again, you don't want to bend the area around the notch since that's where you would place your OEM jack.
12) After the stands are in position, slowly lower the jack and the rear of the car until the car rests on the stands. Verify that the car is stable and supported before working under it. Don't rely on the jack to support the car.