QEMU is a versatile piece of software that has lots of different use cases. Here are some common configurations to (manually...) check.

Emulation mode:

User interfaces:

Guest systems:

Networking card:

Networking attachment:

Disk types:

Graphic access:

Common issues

Make sure you reserve enough memory (-m). For instance, Jessie's default is 128M but running the Stretch installer CD-ROM plain panics with that amount.

ASAN build

LTS/Development/Asan doesn't support static builds, so in addition to the DEB_*FLAGS_APPEND, drop qemu-user/qemu-user-static from debian/control and debian/control-in before building.