Do all your planning before you dig. If possible, select a site with at least 6 hours of direct sunlight. Select the site that can be seen from as many places as possible, including inside the house. The water garden is a 12 month garden. Avoid trees where possible.
Leaves can create a problem in the winter.
Avoid a windy area. The wind can knock the pots over and destroy the plants. Avoid areas which collect run-off. Chemicals from lawns and dirt will collect in the pond and cause problems. Select a material considering both cost and ease of installation.