Place parentheses around a cross-reference

Try using \eqref{fig:label} from the amsmath package.

(Taken from here: https://groups.google.com/forum/#!topic/latexusersgroup/e1CHoBfj8pQ)

You could renew the reference command, perhaps something like:

\let\oldref\ref
\renewcommand{\ref}[1]{(\oldref{#1})}

Here's a complete MWE to play with:

% arara: pdflatex
% arara: pdflatex
\documentclass{article}

\let\oldref\ref
\renewcommand{\ref}[1]{(\oldref{#1})}
\begin{document}

\section{Section heading}\label{sec:testlabel}

Reference: \ref{sec:testlabel}
\end{document}

Note: as mentioned by @Mico, this solution isn't compatible with hyperref package.

I prefer the autoref function provided in the hyperref package.

Taking examples for tables and figures:

The Table reference is \autoref{tab:VHTRC}.
The equation reference is \autoref{eq:3}.

Next, new reference styles should be renewed at the preamble. Usually I define them just after including the hyperref package.

\usepackage{hyperref}
\def\equationautorefname~#1\null{Equation (#1)\null}

The \def define the auto-reference variable #1 in the style Equation (#1), which is enclosed in (). Then you will get the result like this:

If you want to use curly braces {}, they should be escaped with the \.

\usepackage{hyperref}
\def\equationautorefname~#1\null{Equation \{#1\}\null}