One thing I might recommend are these
plastic covers that fit onto the outdoor
outlets. They're made to keep an extension
cord from being pulled-out, plus protect it
from water, but I'm pretty sure one of those
power supplies would fit inside one...
As far as anything else goes. I guess it
depends on the circumstances. For example,
let's say you wanted to mount a camera on a
post watching the house. What I might do is
install a post for bird feeders and houses,
unless there is a tree handy. Then, I would
bury either a heavy extension cord, or use
UF wire and bury it up to the post/tree. I'd
get a water-tight box and run the AC into
that and put the power supply inside it and
seal it up, then run the low voltage wire up
the post/tree and mount the camera in a bird
house to conceal it. Like I said, it's
situational and hard to tell someone what to
do when you don't know the circumstances
involved.