In terms of fonts, I have the following:
\usepackage{charter}
\usepackage[scaled=0.92]{helvet}
\renewcommand{\ttdefault}{cmtt}
\renewcommand{\familydefault}{\rmdefault}
\usepackage[charter]{mathdesign}
\usepackage[T1]{fontenc}
My question is: What are the criteria that tell me the math font is indeed "working well" with the text font (to me, looking at them, sure, they look fine, but why, and would other people agree?).
Secondly, and maybe this is another question altogether, how do I know if my Sans-Serif and Typewriter font fit well with the Roman font? More specifically, do my choices make sense? (Roman = Charter, Sans-Serif= Helvetica and Typewriter=Computer Modern Typewriter).
Many thanks!