Example of use of TikZ beamer styles

testm.tex

\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{arrows,overlay-beamer-styles}

\begin{document}

% mode 1 (but you need to add an  "use as bounding box" 
% somewhere to avoid jumping because adding things changes
% the size of the picture
\begin{frame}
    \begin{center}
        \begin{tikzpicture}[>=stealth',thick]
            \node at (0,0) (1) {$1$};
            \node at (2,0) (2) {$2$};
            \draw<2-> (1) edge[bend left,->] (2);
            \draw<3-> (2) edge[bend left,->] (1);
        \end{tikzpicture}
    \end{center}
\end{frame}

% mode 2, better, now the arrows are drawn always but they are
% invisible on some frames
\begin{frame}
    \begin{center}
        \begin{tikzpicture}[>=stealth',thick]
            \node at (0,0) (1) {$1$};
            \node at (2,0) (2) {$2$};
            \begin{scope}[visible on=<2->]
                \draw (1) edge[bend left,->] (2);
            \end{scope}
            \begin{scope}[visible on=<3->]
                % change color on <4>
                \draw[alt=<4->{red}{}] (2) edge[bend left,->] (1);
            \end{scope}
            % you can use only too:
            \only<4->{
                \draw [red, ultra thick, red, ->] (2) -- (1);
            }
        \end{tikzpicture}
    \end{center}
\end{frame}

\end{document}