Comment
In addition to the built-in latex comment command %, I always define a comment command that can deal with comments spanning line breaks.
in the preamble:
\newcommand{\comment}[1]{}
usage example:
\comment{This is a comment and it won't show up in the output even if it spans more than one line of the input file or the line breaks move around.}
You can also use conditional comments, shown here being used to allow commenting out all figures (very useful for faster previewing).
in the preamble:
\usepackage{ifthen}
\newboolean{includefigs}
\setboolean{includefigs}{true}
\newcommand{\condcomment}[2]{\ifthenelse{#1}{#2}{}}
usage example:
\condcomment{\boolean{includefigs}}{
\begin{figure}
....
\end{figure}
}
From http://www.me.berkeley.edu/~mcmains/latex.html
