Hanging Pictures, is not always as simple an just banging a nail in the wall! Sometimes if the picture is large and heavy it is necessary to use stronger wall fixings. Wall type will also determine what can be hung and where.
I have worked as a gallery manager for 5 years so whilst having the skills to hang a picture I also have an eye for how things can be hung and am happy to offer any advice if required.
Specialist hanging systems are available if you have a need to be changing your artwork regularly. These are more expensive on initial outlay but make hanging so much quicker in the future.