Sometimes the best advice is the telling off you give yourself
Where and When
Elsewhere I have written a tutorial about the importance of doing a map, but it is worth reiterating a few salient points.
Unless your saga takes place over Eons, the chances are that much of the general geography will remain the same. Rivers will be in the same place, mountains are not going to suddenly leap half a mile to the left and your world probably has the same number of moons.
However, some local bits and pieces might change. What was a high street full of nice shops may now be a shopping Mall. The river may have had banks raised and the channel deepened to allow for bigger ships. The corner shop may have changed hands, the bridge might have fallen down...
Because you are writing a saga, you know change is possible during your story in a way that is out of the scope of the average novel, but you must be realistic about it. Work out where your mountain is and list it under "This ain't going nowhere," but list your forest under "might be chopped down and become farmland in two or three generations."
Try to really understand your world, your location, in the same way you understand your characters. If you want to return to a place a few hundred years later and go to the same pub, make sure the pub is built in such a way as it is plausible that it will still be there. So, brick or stone, but probably not featherboarding or mud. If in doubt, err on the side of longevity; if they have an obvious sell by date, then there is a good chance it will come into play somewhere, even just in reference, and catch you out.
If your saga is set in our own world you have an advantage because you can use real maps and real history, but make sure you research you location fully so that you do not make idiotic mistakes that will come back to bite you later. "He was amazed this place was still here after all these years," is probably a cop out for bad planning.
Next: Getting bogged down in detail »
