{ a \choose b } in math mode

N.B. If you are using the amsmath package, using \choose will cause a Package amsmath Warning complaining about the \atopwithdelims control sequence. Just ignore this warning.

9. How do I get a square/cube/n-th power root?

\sqrt{k} for a square root of k
\sqrt[n]{k} for an n-th power root of k

10. How do I get nicely numbered equations?

Use the equation style:

\begin{equation}
E=mc^{2}
\end{equation}

Note: Numbered equations are almost always preferable to unnumbered equations, for which you can use \begin{displaymath} \end{displaymath}.

11. How do I reference numbered equations?

When you write the equation,

\begin{equation}
E=mc^2
\label{eqn:Einstein}
\end{equation}

And then when you wish to reference the equation in the prose,

Applying the mass-energy relations given in (\ref{eqn:Einstein}),
we find that...

Note: the eqn: in the label is not formally necessary, but will make your code more readable.

12. How do I reference numbered figures?

When you insert the figure the equation,

\begin{figure}
\includegraphics{poodles.eps}
\caption{Commuting canine movements}
\label{fig:poodles}
\end{figure}

And then when you wish to reference the figure in the prose,

As seen in Figure \ref{fig:poodles}, the hunting patterns...

13. How do I stop LaTeX from putting an extra space after Ms. ?

use Ms.~Name

14. How do I include a package?

\usepackage{packagename} before \begin{document}
Useful package: amssymb -- mathematical symbols and fonts

15. How do I create a subsection?

\subsection{subsectionname} for subsections
\subsubsection{subsubsectionname} for subsubsections

16. How do I superscript?

$E = mc^{2}$

$1024 = 2^{10}$

17. How do I draw the double-barred Z (representing all integers), R (all reals), or Q (all rationals) in LaTeX?

\mathbb{Z}, \mathbb{R}, \mathbb{Q} (you must be using the amssymb or amsmath package)

18. How do I do italics in LaTeX?

\emph{}

19. How do I get the "for all" symbol (upside down A)

\forall in math mode

20. How do I include an image?

\begin{figure}
\includegraphics{imagename.eps}
\caption{Lovely caption}
\label{fig:somethin-you-will-remember}
\end{figure}

21. How do I rotate or resize an included graphic?

use the angle attribute to \includegraphics. For example, \includegraphics[angle=45]{foo.ps} to rotate counterclockwise by 45 degrees. Other possible attributes are:

\includegraphics[width=5in]{foo.ps} 
\includegraphics[width=\textwidth]{foo.ps} % scale to the width of the page
\includegraphics[height=5in]{foo.ps}
\includegraphics[scale=0.5]{foo.ps} % scale to 50%

If you want it to be just as wide as the text, use width=\textwidth.

22. What does Unable to read an entire line---bufsize=3000. Please alter the configuration file. mean?

Most likely, you are trying to include an image that is not in PostScript format. Or it may be that your image is PostScript generated on a Macintosh, in which case typing

athena% clg filename.eps

should solve the problem.

23. How do I convert a graphic to EPS?

See here.

24. How do I make theorems, lemmata, and so forth?

See this PDF document for the answer.