I now make it my standard habit that after the declaration of the sp i wrap the entire body in a begin end.
declare myProc() as
Once you stub in the solid open and closing it is very easy to fill in the body and even more difficult to accidentally leave something inside the proc.
When you script out stored procedures in SQL 2005, it does not add the 'GO' to the bottom of the script as it did in SQL 2000. Consequently we have developers who script out their stored procedures for the install script and forget to add the 'GO' and end up with bonus commands in their stored procedure (if I don't catch it). So I also made it a best practice to use the begin and end to denote the stored procedure body. This question illustrates the problem.
Thanks for the question.