\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{enumerate}
% Brackets:
% =========
\newcommand{\brk}[1]{\left(#1\right)} % \brk{.} => (.)
\newcommand{\fbrk}[1]{\!\left(#1\right)} % a\fbrk{.} => a(.) for functions...(so there's no space after the letter)
\newcommand{\Brk}[1]{\left[#1\right]} % \Brk{.} => [.]
\newcommand{\BRK}[1]{\left\{#1\right\}} % \BRK{.} => {.}
\newcommand{\brkco}[1]{\left[#1\right)} % \brkco{.} => [.)
\newcommand{\brkoc}[1]{\left(#1\right]} % \brkoc{.} => (.]
\newcommand{\abrk}[1]{\left<#1\right>} % \Average{.} => <.>
% Blackboard bold (integers, rational numbers,...):
% =================================================
\newcommand{\CC}{\mathbb C}
\newcommand{\RR}{\mathbb R}
\newcommand{\QQ}{\mathbb Q}
\newcommand{\ZZ}{\mathbb Z}
\newcommand{\NN}{\mathbb N}
\newcommand{\A}{\mathbb A}
\newcommand{\HH}{\mathbb H}
% Set Theory:
% ===========
\newcommand{\union}{\bigcup}
\newcommand{\intersection}{\bigcap}
\newcommand{\isom}{\simeq}
% Environments:
% =============
\newtheorem{thm}{Theorem}[section]
\newtheorem{remark}[thm]{Remark}
\newtheorem{example}[thm]{Example}
\newenvironment{solution}{\begin{proof}[Solution]}{\end{proof}}
% Miscellaneous:
% ==============
\newcommand{\imples}{\qquad\Longrightarrow\qquad}
\newcommand{\e}{\epsilon}
\newcommand{\eps}{\varepsilon}
\newcommand{\sequence}[3]{{#1}_{#2},\ldots,{#1}_{#3}}
\newcommand{\tr}{\mbox{\rm tr\,}}
Do you want an actual TeX file containing all of this?