For a complete Manual of Style: The Chicago Manual of Style.
Create spaces to align in math mode:
% Create a box with same height, depth, and width as subformula.
\phantom{subformula}
% Zero witdh box with same height and depth as subformula.
\vphantom{subformula}
% Zero height and depth box, and same width as subformula.
\hphantom{subformula}
Bold vectors and matrices:
\renewcommand{\vec}[1]{\mathbold{#1}}
\newcommand{\mat}[1]{\mathbold{#1}}
booktabs for clean and nice-looking tables.
% Needs: \usepackage{booktabs}
\begin{table}
\centering
\begin{tabular}{lrr}
\toprule
& \multicolumn{2}{c}{Data} \\
\cmidrule(lr){2-3}
Name & A Column & Another column \\
\midrule
Some data & 10 & 95 \\
Other data & 30 & 49 \\
\addlinespace
Different stuff & 99 & 12 \\
\bottomrule
\end{tabular}
\caption{Some data.}
\label{table:nice-label}
\end{table}
siunitx package to format numbers, currencies, units, etc:
% Needs: \usepackage{siunitx}
\sisetup{
round-mode = places,
round-precision = 3
}%
Cost: \SI{100}{\$}.
Display percentage: \SI{50}{\percent}.
Rounding numbers: \num{1.23456}.
The include command can be used to compile a subset of files. Cleans pages before and after including the code.
Note: It is not possible to nest includes.
\includeonly{chapter1}
% ---
\include{chapter1}
\include{chapter2}
\include{chapter3}
The input command can also be used. It is a lower-level command, but works in nested files.
Microtype tries to enhance the appearance and readability of the document while exhibiting a minimum degree of visual obtrusion.
\usepackage[activate={true, nocompatibility},
final, % Use draft to disable.
tracking=true, % Letter-spacing.
kerning=true, % Adjust spacing of of scpecial characters.
spacing=true, % Enable spacing between characters.
%stretch=10, % Default stretch can blur the text.
%shrink=10, % Default shrink can blur the text.
]{microtype}
\SetTracking{encoding={*}, shape=sc}{50} % Just personal preference.
Note: It is recommended to disable protrusion in TOC, LOF and LOT.
\microtypesetup{protrusion=false} % disable protrusion
\tableofcontents % print Table of Contents
\microtypesetup{protrusion=true} % enable protrusion again
Allow equations to be copied (from StackExchange):
% Needs: \usepackage{accsupp}
\newcommand\copypastable[1]{%
\BeginAccSupp{method=escape,ActualText={\detokenize{#1}}}%
#1%
\EndAccSupp{}%
}