In a way it's kind of up to you and you need to make some choices. The manual would say on the pinch welds. But to safely raise the car without a lift, you need to be placing both a jack AND axle stands. Below is what I like to do, but you can always do vice versa and swap the jack and axle stand positions.
I like to place the axle stands on the pinch welds (the reinforced portion of the sill recommended in the manual). I do this because jacking at those points, while viable, can bend or damage the pinch welds. Also, I like to have my axle stands as far out to the edges as possible for maximum stability. I've found it's better to raise the car, and then use those reinforced points for the axle stands to support. The pinch welds are not hidden on a MY16 PP car. The plastic runner trim is on the outside. Look a couple inches in and you will see the sill. Near the fenders are the reinforced sections, only 3-4 inches in length. Not sure about little arrows but it should be fairly obvious what part is reinforced as it will be thicker and protrudes down a bit.
Here is a pic with the axle stand placed on the front "pinch weld":
So if placing the axle stands on the pinch welds, the question becomes where to place the jack itself?
FRONT:
I used to use the subframe bolt discussed earlier in this thread (near the lower control arm). This worked fine but is a little hard to reach depending on the size of your jack. Here is a pic of that:
But since, I have retrofitted the Audi jack pads and they work excellent as a jacking point, and still give room to place an axle stand on the pinch weld. Pics of that in action:
REAR:
Can jack on the box with the plastic grommets (just a bit further in than the pinch weld) like this:
But for me a wise investment was a set of automotive ramps. I just back the rear on to those, and do jack and stands in the front only.
But you need to swap a rear tire!! Well... it's easy to get both wheels on one side of the car off the ground by jacking from the front alone. The wheelbase is short enough where the whole side is lifted.
Pic of ramps:
Not the greatest pics but hopefully that was helpful.
P.S. Not sure what you mean by scissor jack but if it's the jack that comes in the trunk... I would highly recommend picking up a hydraulic floor jack if you plan on lifting the car outside of emergency situations (like flat tire). You can get a hydraulic jack for fairly cheap and they are less dangerous.
