Professional looking tables
When you come from a mickeysoft world, you are used to tables that contain more lines than useful information. If you try to replicate this in \(\LaTeX{}\) you end up with something like the following

\begin{tabular}{|c|c|c|}
\hline
\bf Item & \bf Category & \bf Purchase cost\\\hline\hline
car & vehicle & expensive\\\hline
apple & fruit & cheap\\\hline
bus & vehicle & very expensive\\\hline
yubari king melon & fruit & Expensive\\\hline
\end{tabular}
The problem with this type of table formatting is that the lines distract your brain from looking at the data. It is much better to typeset tables using the booktabs package. You just include it in your preamble:
\usepackage{booktabs}
Once you've done that, you can set professional looking tables like:

\begin{tabular}{ccc}
\toprule
\bf Item & \bf Category & \bf Purchase cost\\
\midrule
car & vehicle & expensive\\
apple & fruit & cheap\\
bus & vehicle & very expensive\\
yubari king melon & fruit & expensive\\
\bottomrule
\end{tabular}
You can find the documentation of the package on CTAN online. You can also draw partial horizontal lines, called cmidrules.