One of the easiest ways to change the look and feel of your messaging is to change the font. It’s easy to do so for for PDFs and printed materials it. And these days it’s pretty easy to do on the web as well.
First, you’ll need a source of high-quality fonts. First stop is Font Squirrel, the preëminent site for free fonts. If you don’t know where to start, I recommend their most popular list. I’m partial to sans serif fonts. My favorites are Aller, Source Sans Pro, Lato, Open Sans, Montserrat, and the PT family. The all have proper italics (except Montserrat which is display font, intended only for headers). You can tell by looking particularly at the a and g characters, where the plain typeface has double-story versions, but the italic version are single-story.
For web pages, all modern browsers support the @font-face CSS declaration. And while you can host your own web fonts on your site, Google makes it super easy by simply pointing at the fonts they host on...wait for it...Google Fonts. There are premium 3rd party services you can use as well, like Typekit (owned by Adobe).
On the web and in HTML emails, you will want to construct what’s known as a font stack. When crafting mine, I try to avoid fonts that either don’t have a proper italic, or the italic they have is simply a boring, slanted version of the plain typeface. Here’s one I’ve used:
font-family:'Source Sans Pro','Segoe UI',Corbel,Roboto,'Gil Sans',sans-serif;
The first font—Source Sans Pro— will only work in apps that support the @font-face declaration. Unfortunately—while all modern browsers support this—few email apps do. Hence the fallback to Segoe UI (PC), Corbel (Mac with Office installed), Gill Sans (Mac without Office and iOS) and Roboto (Android devices). Any Mac without Office, or other operating systems (Linux) will just use their default sans serif font.
It’s a travesty that the Mac doesn’t ship with a sans serif font that has a decent italic. Gill Sans is as close as it gets, but I find the tiny counters and low x-height make it difficult to read on screen. I still prefer it to Helvetica, though.