Landscape Design Criteria - Ideally, your pond should fit into the general landscape theme or design applied to the rest of your yard. A formal pond in an informal landscape would be as out of place as an informal pond would be on the grounds of Versailles Palace. The color, texture and line of the pond and its surroundings should match too. 

Points of View - Try to determine the dominate viewing point for the pond as part of the layout process. If you spend most of your time on your deck, situate the pond so that it may be seen and heard from that vantage point.

Pond Shape - Formal ponds will have a regular, geometric shape such as a square, rectangle or circle with well defined edges and corners. A formal pond is meant to show the viewer that it was created by a human and not by nature.

Informal ponds should have irregular lines. Mother nature rarely creates natural ponds with straight lines and neither should you. An informal pond should remind the viewer of a pond in the woods.

Staking the Outline - Before putting the shovel in the ground, take some wooden stakes and a length of string and stake out the outline of the pond. This will allow you to have a more concrete idea of how the pond will look. It is better to realize that something is not right at this point rather than after you have removed the soil.