Work Area Organization
If vehicle maintenance is to remain just a hobby, the external conditions should match this.
Always support the vehicle on stands!
Jacks are only suitable for lifting the vehicle. They cannot serve as a reliable support when working under the vehicle. Even in the greatest hurry, never forget proper support for the raised vehicle!
To secure the vehicle while it is raised with a jack, the wheels must be chocked. To do this, place stones, wooden or metal wheel chocks, or other objects under the wheels to prevent the vehicle from rolling.
What is suitable as a support?
Hollow concrete blocks have proven to be an inexpensive support option. However, they must not be damp or cracked, otherwise they may collapse under load. A board must be placed between the block and the body so that the load is distributed evenly over the entire surface of the block. The block itself must stand with its holes facing up (vertically) on a flat surface capable of bearing the load (concrete or asphalt).
Support stands are the ideal complement to a garage jack. However, there is a risk that when one side of the vehicle is raised, the stands placed on the other side may tip over if the tripod is positioned incorrectly. It is best to place the stands so that one leg points outward and two point toward the inside of the vehicle. The stands must have a sufficient support base!
A lift is certainly the best support option, since no jack is required. In addition, the vehicle is held quite securely.
Jacks
There are many jack designs, one for every budget and every purpose. Some of them are listed here:
Scissor jack: always place a small board under the jack base so that it does not sink into the ground.
Parallelogram-type jack: only purchase a sturdy design. Such a jack is also suitable for work on a vehicle whose body is already slightly deteriorated at the lifting points. In that case, the jack can be positioned closer to the center of the body.
Hydraulic plunger jack: before purchasing, check the lifting height. A jack that is too short will not raise the wheels high enough. A jack that is too tall cannot be properly positioned under the vehicle.
Garage jack: for those who prefer to work independently, a short, compact garage jack that is easy to store is a good choice.

The scissor jack (2) may only be placed under the lifting point marked on the body (1) in the sill slot of the vehicle underbody. This must be observed both at the front and at the rear.

A garage jack is also positioned under the marking (1). However, in this case it is better to use the side member under the body. To avoid damaging it, place a board (2) between the jack and the body.
Never forget to place supports when working under the vehicle!
Test yourself
A quick Audi 80 quiz: every answer comes with an explanation and a link to the manual page.