

When using p.save, use resolution=96 to make a plot the same size as
the displayed plot.

--
When making encapsulated postscript (eps) files the output font will
always be smaller than the screen font. Therefore you should set the
screen font bigger than it needs to be, or increase font size
immediately prior to creating the eps file (use p.font_size=).

--
For image objects, the default is to make the plot (in pixels) as big
as the image, irrespective of the size of the plot window. To make a
more natural size, set margin=0.10, for example.

--
When you plot new data on top of existing data, the object plot will
automatically adjust the X and Y-ranges to fit the new data:

p=plot(findgen(5))
q=plot(-findgen(10),/overplot)

If you don't want this to happen, then do:

q=plot(-findgen(10),/overplot,xrange=p.xrange,yrange=p.yrange)

--
If you're going to create many similar plots and don't want to set
thick, font_size, color, etc., for each one of them, then you can do:

extra={thick: 2, font_size: 16, color: 'red'}

IDL> for i=0,5 do p=plot(findgen(5),_extra=extra)

--
If plotting a spectrum using a histogram-style plot (done with psym=10
in direct graphics), do NOT use the /histogram keyword. The /stairstep
keyword is the one to use.
