While there’s no rich text editor in Google+, there are still ways to add a bit of markup to your text to make it look better. Here are a few things that you can do:
To make a word bold, simply put it between asterisks, like this: text
To make a word italicized, simply put it between underscores, like this: text
To add a
strikethrough to text, simply put it between dashes, like this: -text-
These tips work for posts as well as comments, so use them often!