The todo package provides powerful commenting options for latex writers. I made some setups to fit to my flavor.
I used this setup since early 2018. This makes three different kinds comments: inline comment, urgent comment (inline but with an orange color), and side comment.
(Note) Make sure you include the setspace package.
\usepackage{hyperref}
\usepackage{setspace}
\usepackage[textsize=small, shadow, textwidth=1.5cm, backgroundcolor=yellow]{todonotes}
\makeatletter
\renewcommand{\todo}[2][]{%
\@todo[caption={#2}, #1]{\begin{spacing}{0.5}#2\end{spacing}}%
}
\newcommand{\inlinecomment}[1]{\todo[inline]{ #1}\noindent}
\newcommand{\urgentcomment}[1]{\todo[color=red!70, inline]{[URGENT] #1}\noindent}
\newcommand{\sidecomment}[1]{\todo[fancyline]{\scriptsize #1}}