The three comics all the examples are from are A Sickness in the Family by Denise Muso (published 2010), Book 10 of Y the Last Man by Brian K. Vaughan, Pia Guerra and Jose Marzan, Jr. (published 2008), Volume 6 of Buffy the Vampire Slayer by Joss Whedon, Jane Espenson and Georges Jeanty (published 2010).
For starters, the first convention I noticed is that all text is in CAPITALS IN A SANS SERIF FONT THAT LOOKS SUSPICIOUSLY LIKE COMIC SANS (well, that’s presumably the reason it’s called comic sans). I imagine this is because text is presented in small snippets usually less than two sentences long. Serif fonts are easier to read for long pieces of running text, but sans serif is great for a less cluttered look.
The next thing I noticed is that words that the characters are speaking aloud go in round speech bubbles, whereas thoughts go in square text boxes:
|pictures on the left from A Sickness in the Family, pictures on the right from Buffy the Vampire Slayer|
Square text boxes also seem to be used to show a change of scene, or give information to the reader about a new place or character.
Bolding combined with italics seems to be used for emphasis, the same as in non comics. Even so, I find it hard to tell when emphasis is being used:
By far my favourite font aspect of the comics is the fonts used to depict sounds.
|Top row from A Sickness in the Family, middle row from Buffy the Vampire Slayer, bottom row from Y the Last Man|
I particularly like this bit of ‘sound type’ in the picture below from A Sickness in the Family. The letters are distorted like a rising tendril of smoke, evoking a high pitched hissing noise.