One of my “customers” wanted a book that didn’t look so “sciency” (i.e., less like LaTeX). So here are a few tweaks to match their expectations.

Chapters should have letters as references with the prefix “Teil”:

\renewcommand{\thechapter}{Teil \Alph{chapter}}

Sections have the letter, a hyphen and the number:

\renewcommand*{\thesection}{\Alph{chapter}-\arabic{section}} 

Figures have no numbers, only the caption text below (using the package caption):

\usepackage{caption}
\captionsetup[figure]{labelformat=empty,textfont=footnotesize}
\renewcommand{\thefigure}{}

The first line of a paragraph is not indented. To compensate, the space between paragraphs is bigger:

\setlength\parindent{0pt}
\addtolength\parskip{4pt}

The header line of a page contains no section, but only the name of the chapter (using the package scrlayer-scrpage):

\usepackage{scrlayer-scrpage}
\clearpairofpagestyles % empty default header/footer markings
\automark[chapter]{chapter} % only chapter as mark
\ihead{\headmark} % inner margin has name of chapter
\ohead{\pagemark} % outer margin has page number