    To see a quick version of your picture, render it very small.  With fewer
 pixels to calculate the ray tracer can finish more quickly.  -w160 -h100 is
 a good size.

    Use the +Q 'quality' switch when appropriate.

    If there is a particular area of your picture that you need to see in
 high resolution, perhaps with anti-aliasing on (perhaps a fine-grained wood
 texture), use the +SC, +EC.  +SR, and +ER switches to isolate a 'window'.

    If your image contains a lot of inter-reflections, set max_trace_level to
 a low value such as 1 or 2.  Don't forget to put it back up when you're fi-
 nished!

    'Turn off' any unnecessary lights.  Comment out extended light and spot-
 light keywords when not needed for debugging.  Again, don't forget to put
 them back in before you retire for the night with a final render running!

    If you've run into an error that is eluding you by visual examination,
 it's time to start bracketing your file.  Use the block comment characters
 (/* ...  */) to disable most of your scene and try to render again.  If you
 no longer get an error, the problem naturally lies somewhere within the dis-
 abled area.  Slow and methodical testing like this will eventually get you
 to a point where you will either be able to spot the bug, or go quietly in-
 sane.  Maybe both.

    If you seem to have 'lost' yourself or an object (a common experience for
 beginners) there are a few tricks that can sometimes help:
       1)   Move your camera way back to provide a long range view.  This may
            not help with very small objects which tend to be less visible at
            a distance, but it's a nice trick to keep up your sleeve.
       2)   Try setting the ambient value to 1.0 if you suspect that the ob-
            ject may simply be hidden from the lights.  This will make it
            self-illuminated and you'll be able to see it even with no lights
            in the scene.
       3)   Replace the object with a larger, more obvious 'stand-in' object
            like a large sphere or box.  Be sure that all the same transfor-
            mations are applied to this new shape so that it ends up in the
            same spot.
