Where should jack stands be placed, both front and rear?

Open u? Can you post pic?

Depending on what you need to work on? they will work fine under the lower control arms, when the weight comes down the suspension will settle and they will be firm. body pinch welds, at rear on suspension arms or body pinch welds, get the weight on the stands and give a little shake just to make sure it has settled, work on firm flat concrete floor as well, if in doubt get someone with more experience to check first hand as to the positioning of the stands.

Heres a guide on that subject, it will help

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

And a video

https://youtu.be/xLFn_bMkZc0

If you follow the pinch weld along the bottom of the vehicle, in front of the rear tires you will see a place for a jack. That is where I recommend.