The habit of keen observation will save you from a legion of pitfalls. The more you train your eyes to see, and your mind to retain what you have seen, the less chance there is of your putting down inaccuracies.
I have been reading a MS. wherein the heroine—a beautiful girl with a face like a haunting memory (whatever that may look like)—spent a whole afternoon lying full-length on the grass, the first sunny day in February, revelling in the scent of violets near by, and watching the swallows skimming above her. If the writer had no opportunity to observe the comings and goings of swallows, she might at least have turned up an encyclopædia, when she would have found that swallows do not arrive in England till well on into April.
Then, after 249 more pages, the beautiful girl finally died of a broken heart—obviously absurd! In real life she would have died on the very next page of rheumatic fever and double pneumonia, after lying on the wet grass all that time!
Frequently, when I point out similar errors to the novice, I get some such reply as this, "Of course, that reference to swallows was only a slip of the pen"; or, "After all, it is merely a minor point whether she lay on the grass or walked along the road; it doesn't really affect the story as a whole."
True, such discrepancies may be only minor details; but, on the other hand, they may not. I have noticed, however, that the writer who is inaccurate on small points is equally liable to inaccuracy where the main features of the story are concerned; and the writer who does not know enough about his subject to get his details right seldom knows enough about it to get any of it right.
The Assessment of Spiritual Values
There is one aspect of life that can only be learnt by observation; a phase of your training where books and lectures can be of but little assistance to you. Important as it is that you should note the material things relating to your subject, it is still more important that you should train yourself to note the psychological bearings and the spiritual values of life, since these are often of far more vital consequence to a story than the plot.
By "spiritual values" I do not necessarily mean anything of a directly religious quality. I use the term to signify the revelation of mind and heart and soul of the various characters that a writer presents, as distinct from a catalogue of externals; the reading of motives, and the recognition of the forces that are within us, as distinguished from the chronicling of superficial items.