1. Park on level surface.
2. Emergency brake on, fully!
3. Chock block the wheel, any old 2X4 will do, just make sure both wheels are blocked to avoid movement and rolling when jacking.
4. Have jack stands at the ready before jacking, on either side of the car if you are lifting one end.
5. Find the lift point and have a old piece of wood to put on the jack surface (to avoid any damage to the body) if you can start pumping.
6. Adjust stands and put under the frame or other jacking point. You want to put the stand in a place to give the car the most stable resting position, towards the side of the vehicle.
7. As Ashman said, lower the jack until there is pressure on the stands and you are sure they can fully support the weight in case of accident. I usually lower the vehicle fully onto the stands and then lift the jack again to take some of the load.
8. When finished working on the car, take some time to do a thorough inspection of your work area and the rest of the undercarriage, you will be surprised at the unexpected things you may find under there for your next weekend!
Happy New Years.