Germans being Germans, there is a systematic approach to Z-Scale layout construction. If you are unfamiliar with layout design, you can use this approach to get running quickly.
When you buy an average Märklin starter set, there is enough track to produce a basic oval. This oval has an 8590 terminal track, a single piece of 8500 straight track and four 8520 curves and six 8521 curves. The mix of the two different curves provides the basis for an organized pattern of track extension that culminates in a completed layout capable of supporting several trains. This approach is often called SETTT, with the starter set having the “S” component and the additional tracks sets being “T-1”, “T-2” and “T-3”.