Path

if [ -d "$HOME/bin" ] ; then
  export PATH=$HOME/bin:$PATH
fi

From my ~/.bashrc:

# funky function nicked from Red Hat and altered a little
# adds entries to the PATH at the start or end and only if the dir exists
pathmunge() {
    if ! echo $PATH | /bin/egrep -q "(^|:)$1($|:)" && [ -d $1 ] ; then
        if [ "$2" = "after" ] ; then
            PATH=$PATH:$1
        else
            PATH=$1:$PATH
        fi
    fi
}

# add some useful PATH entries
pathmunge /usr/local/sbin
pathmunge /usr/sbin
pathmunge /sbin
pathmunge $HOME/bin after
pathmunge $HOME/opt after

# clean up
unset pathmunge