The best practice depends completely on your business and technical requirements.
If you want to have more than one broadcast domain (VLAN) at each end of the wireless link, then you need to trunk.
If you want exactly one broadcast domain at each end of the wireless link then you should use access-mode
If you want different broadcast domains at each end of the wireless link then you should use a routed interface (Layer 3).
In a nutshell you need to think of the wireless bridge as a very expensive piece of copper wire that joins together two switches. The more you use it the more it costs, therefore architect your network accordingly.
Personally I would architect my network so that broadcast traffic did not traverse the wireless, this would require a routed interface on each switch interface that was connected to my wireless bridges.
But this might not work for you as it might require multicast or any other protocol that relies on boradcast traffic.
Cheers.
-Rowan
