PulseAudio depends on a dbus system daemon. Make sure the dbus service is enabled.

For applications which use ALSA directly and don't support PulseAudio, the alsa-plugins-pulseaudio package can make them use PulseAudio through ALSA.

The PulseAudio package comes with a service file, which is not necessary in most setups - the PulseAudio maintainers discourage using a system-wide setup. Instead, PulseAudio will automatically start when needed.

There are several methods of allowing PulseAudio to access to audio devices. The simplest one is to add your user to the audio group. Alternatively, you can use a session manager, like elogind.