Preparing the Drawing for an Oil Painting by Don Finkeldei: A loose, quick drawing on the canvas is better than a detailed drawing.  Make your lines very loose.

 I don’t worry too much about getting the shapes exactly right.  It’s basically an indication of where I want to put things.  Just indicate where they go without drawing the whole thing out.  For instance, on buildings I indicate the roof lines loosely.  I don’t draw in doors, windows, etc.  One thing to note about doing line drawings is that lines make you subconsciously paint up to them sharply.  You don’t want to do that.  A painting works with masses and edge variation.  A line drawing doesn’t use masses and edges so don’t make your lines so distinct that it forces you to keep sharply within them.  That’s why a loose drawing is better than a very detailed drawing.  Don’t worry about painting up to lines.  You can refine the detail later.

 Example of a preliminary sketch by Doug Higgins.  http://www.dhfa.net .  Doug also has a very good online book and is one of the best landscape painters in the U.S.