Are you going to want a pond (water feature) with primarily plants like lilies, and hyacinth? or just fish, or both.
Ponds for certain plants will need at least partial sun.
A pond with only fish, might be better off in total shade to avoid algae blooms, and temp fluctuations.
Certain trees too close to a pond with fish can be a concern, because of toxicity (black walnut comes to mind)..
Electricity can also be a concern, because for pumps you may want your pond near or at least a reasonable distance from a GFI outlet.
Is your yard fenced?
Liability can be a problem, if not fenced.