This article is from the Piano Purchase and Maintenance FAQ, by Isako Hoshino email@example.com with numerous contributions by others.
Research the moving companies. For many local moves, there
are professional piano movers who specialize in piano moving.
Ask what kind of experience they have with piano moving, and
the methods they use to move the piano. Also see if they can
give you any references from other customers.
Take very detailed photos of the piano. You will need these
in case any damage was done to the piano during the move, you
have proof that it was okay before the move.