In my posts with fonts and colors:
Color - I use the lime green color because is stands out from the black background. I was going to have a light blue or white hue, but I since I mostly posted in a light green color, I allowed it to stick.
Font - I used to use Verdana and Times New Roman, but I decided to use a font I didn't often use. So, I chose a font called, "Century," it's a bit between Times New Roman and Georgia, but not entirely and I liked it. Thus, it stayed.
Style - I don't really have a solid style. I often post in varied ways being from centered, listed, included a small image, ect. Whatever I think would be appropriate for the topic.