[Tex/LaTex] Help with adjusting line-spacing on custom title page

Question

I'm making a custom title page for my PhD proposal, following the Title Creation article of LaTeX in Wikibooks. However, after many tries I just can't get the title to have a bigger line-spacing. I was wondering if anyone can help me with this issue.

Heres the image of the issue and a sample document:

Sample Document:

\documentclass[10pt,a4paper]{article}

\usepackage[portuguese]{babel}
\usepackage[latin1]{inputenc}  
\usepackage[pdftex]{graphicx}

\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\begin{document}

\begin{titlepage}
    \begin{center}

    % Upper part of the page
    %\includegraphics[width=0.15\textwidth]{./logo}\\[1cm]    
    \textsc{\large Department}\\[0.5cm]
    \textsc{\Large University}\\[3.5cm]

    \textsc{\Large Proposal bla bla}\\[1.5cm]

    % Title
    \HRule \\[0.4cm]
    {\Huge \bfseries Proposal title proposal title proposal title proposal title proposal title proposal title}\\[0.4cm]
    \HRule \\[1.5cm]

    % Author and supervisor
    \begin{minipage}{0.4\textwidth}
    \begin{flushleft} \large
        \emph{Autor:}\\
        John Smith
    \end{flushleft}
    \end{minipage}
    \begin{minipage}{0.4\textwidth}
    \begin{flushright} \large
        \emph{Orientador:} \\
        Dr.~Albert \textsc{Einstein}
    \end{flushright}
    \end{minipage}

    \vfill

    % Bottom of the page
    {\large \today}

    \end{center}

\end{titlepage}

\end{document}

Answer 1

You are changing the font size to \Huge inside a group, but the group ends before the paragraph, so the line spacing for \Huge has no effect; to correct this, you must end the paragraph (using \par, for example) before closing the group:

\documentclass[10pt,a4paper]{article}

\usepackage[portuguese]{babel}
\usepackage[latin1]{inputenc}  
\usepackage[pdftex]{graphicx}

\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\begin{document}

\begin{titlepage}
    \begin{center}

    % Upper part of the page
    %\includegraphics[width=0.15\textwidth]{./logo}\\[1cm]    
    \textsc{\large Department}\\[0.5cm]
    \textsc{\Large University}\\[3.5cm]

    \textsc{\Large Proposal bla bla}\\[1.5cm]

    % Title
    \HRule \\[0.4cm]
    {\Huge \bfseries Proposal title proposal title proposal title proposal title proposal title proposal title\par}

\vspace{0.4cm}
    \HRule \\[1.5cm]

    % Author and supervisor
    \begin{minipage}{0.4\textwidth}
    \begin{flushleft} \large
        \emph{Autor:}\\
        John Smith
    \end{flushleft}
    \end{minipage}
    \begin{minipage}{0.4\textwidth}
    \begin{flushright} \large
        \emph{Orientador:} \\
        Dr.~Albert \textsc{Einstein}
    \end{flushright}
    \end{minipage}

    \vfill

    % Bottom of the page
    {\large \today}

    \end{center}

\end{titlepage}

\end{document}

which produces:

If you want to increase even more the line spacing, you can change \linespread for the title; a little example using \linespread{1.5} (notice again the \par command necessary for the change to have effect):

\documentclass[10pt,a4paper]{article}
\usepackage[portuguese]{babel}
\usepackage[latin1]{inputenc}  
\usepackage[pdftex]{graphicx}

\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}

\begin{document}

\begin{titlepage}
    \begin{center}

    % Upper part of the page
    %\includegraphics[width=0.15\textwidth]{./logo}\\[1cm]    
    \textsc{\large Department}\\[0.5cm]
    \textsc{\Large University}\\[3.5cm]

    \textsc{\Large Proposal bla bla}\\[1.5cm]

    % Title
\linespread{1.5}
    \HRule\\
    {\Huge\bfseries Proposal title proposal title proposal title proposal title proposal title proposal title\par}

\vspace*{0.4cm}
    \HRule\\[1.5cm]

\linespread{1}
    % Author and supervisor
    \begin{minipage}{0.4\textwidth}
    \begin{flushleft} \large
        \emph{Autor:}\\
        John Smith
    \end{flushleft}
    \end{minipage}%
    \begin{minipage}{0.4\textwidth}
    \begin{flushright} \large
        \emph{Orientador:} \\
        Dr.~Albert \textsc{Einstein}
    \end{flushright}
    \end{minipage}

    \vfill

    % Bottom of the page
    {\large \today}

    \end{center}

\end{titlepage}

\end{document}