You should look at the comment package. It is specifically meant for this purpose. It provides a comment environment (or a \comment...\endcomment command pair) that you need to encompass your don't-want-to-compile stuff with. It also allows a form of version control, versionA (say), which can be turned on/off using \includecommand{versionA}/\excludecomment{versionA}. Such version-specific comments have their own environment: \begin{versionA}...\end{versionA} or the \versionA...\endversionA command pair.
Here's a minimal working example (the second paragraph \lipsum[2], prefixed with 2., is not typeset):
\documentclass{article}
\usepackage{comment}% http://ctan.org/pkg/comment
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\begin{document}
1.\ \lipsum[1]
\begin{comment}
2.\ \lipsum[2]
\end{comment}
3.\ \lipsum[3]
\end{document}
