All comments must be complete sentences. Start with a capital letter, and end with a fullstop.
Function calls should have no extra spaces around the (), so function( x ), should be written function(x).
Functions calls with more than one parameter should have spaces after the argument, so function(x,y,z), should be function(x, y, z).
Limit line length where possible to 80 characters.
All SQL statements should use uppercase for SQL keywords, and lowercase for everything else.