Getting people to leave me the hell alone.
When I knew people wouldn't be bugging me, I would be
generating work, but once there even was the possibility
of people coming by I wasn't able to work as well. When I
had time to hit a stride then I could keep working until
someone actually came up and asked for something. Sometimes
it meant coming in a 6 in the morning, but at 9-10am when
everyone else got there, work started sputtering. But
that was just my experience at one company.
To help ensure privacy with no distractions while
trying for that alpha state I
found that music helps. Antisocial behaviour can get
certain people to avoid you, but it tends to show up
in reviews.