Be exact also with your values. If your study is not sure of its values, it will weaken the results you should get from it later.
Make your studies in the same light as that which the picture will represent. You can paint a picture under any light you please if your studies give you the facts as to light and shade that the truth to nature requires; but studies made in one light for a picture representing another are useless to that picture.
No good painting was ever made without preliminary studies. When you are to make a picture, therefore, take plenty of time to prepare yourself with all the material in the form of facts that you may require. Don't trust to building up a picture from a sketch or two and your "general knowledge." That sort of thing is something which a painter of experience may do after storing his mind for years with all sorts of knowledge; but it will not do for most people--least of all for a student. And it is a dangerous way for any one to work. Even the experienced painter is apt to do the worse work for it, and if he does so constantly, his reputation may suffer for it. Take time to be right.
[Illustration: =Study of a Blooming-Mill.= _D. Burleigh Parkhurst._]
Don't be afraid of taking measurements. Every one who did anything worth looking at took measurements. Leonardo laid down a complete system of proportions. You can't get your proportions right without measurements, and if your proportions are not right, nothing will be right. Use a plumb-line: use it frequently, and measure horizontals and verticals. If you are in doubt about anything, stop a minute and measure. It takes less time than correcting.
Whatever you do, get the character first, then the details. Character is not a conglomeration of details. The detail is the incident of character. See what the vital things are first, then search farther.
Use your intelligence as well as your eye and hand. Think as you work. Don't for a moment let your hand get ahead of your brain. Don't work absent-mindedly, nor without purpose. If your mind is tired, if your eye won't see, stop and rest a while. Tired work runs your picture down hill.
The name of still life is used in English for all sorts of pictures which represent groupings of inanimate objects except flowers. The French word for it is better than ours. They call it "_nature morte_" or dead nature.