Specific reasons not to use Comic Sans font.?

It's more a question of what you are using a font for that is important. Comic Sans has often been given bad press because it is used so much by teachers, leaders etc working with young children (it is a very good font for young children learning to read).

Fonts convey something about the person/company using them. A bank/major company wants to be taken seriously by customers so it wouldn't use a font like Comic Sans for signs or correspondence.

It really depends on the reason for using the font. There is nothing wrong with the font Comic Sans in itself. It is well-constructed, easy-to-read and friendly but it has definitely been overused by junior schools and kindergarten..

DO NOT use a serif and san serif font together. Pick one or the other. That's typography 101 stuff. For body text, you need to be concerned with readability. I prefer using (and reading resumes that use) san serif fonts. Helvetica Arial Akzidenz-Grotesk Univers As a graphic designer, you're allowed more wiggle room for experimenting with header and sub-head fonts, so pick a theme. Don't go nuts though. There really shouldn't be any reason for using more than two different fonts. Anything more than that will get distracting and look like you don't know your basics. Good Luck :)