Here's a little more detailed info sheet for guest strips submissions:

• Comic format is preferred, and usually is chosen over illustrations, but the latter can also work.
• No particular theme to follow, but if you want ideas here are a few words that resonate with the spirit of GGaR: gratitude, room-mates, friendship, dreams & stories, positive body image, queer love, etc...
• Please stay with the canon story, unless it's obvious it's a fun alternative universe (like this guest strip, or this one), if you want to make fanservice fanarts I will totally reblog it but not here ;)
• Comic formats, colors, and number of pages are up to you. The strip's width works best between 900p and 1100p. 
• Here are some examples of previous Guest Strips!
• Deadline is on the 20th of December
• Submit your Guest Strip entry to gogetaroomie@gmail.com (with the mail title "Guest Strip")

Any questions can be sent via my twitter, tumblr or the above email address. 

Cheers<3