Next you need to select a specific location for your artwork. There are a number of factors to consider when doing this.

You need to have access to a water hose and electricity.

The surface needs to have a lot of embedded dirt so that your drawing will stand out. It also helps if the color is relatively uniform.

Smoother surfaces will allow you to make finer details. It is also easier to adhere tape to smooth surfaces. However, it is more difficult to be precise with very smooth surfaces. When you spray the target area, the water will spread out when it hits the surface and it will also clean off the area immediately around it. This is less of an issue with rough surfaces because the water is scattered by the surface texture.

Sidewalks are plentiful and easy to work with. But keep in mind that people will be walking all over it. So your drawing won't last as long.

With all this in mind, find the best location that fits your needs.