Star is my fursona. Ze is what I use to represent myself to the internet, for the most part. I don't consider zem a part of me, ze is me. It even feels weird to refer to zem in third person. As is such, I would never depict zem doing anything I would not do. Similarly, anything other people depict them doing I assume they want me to do/do to me, unless I commission the picture. So:

DON'T
-Depict zem being sexual with anyone besides Hootie, Freyja, Satch, or M-ree, nor engaging in penis-in-vagina sex with anyone besides Hootie & Freyja without a condom without my expressed permission.
-Depict with any of the "No" fetishes on my f-list
-Alter zer design/anatomy - here is what I consider altering zer anatomy
-Depict zem being violent without protecting someone/themselves or without my expressed permission
-Depict zem as pregnant
-Depict zem producing milk unless feeding a baby
-Depict zem inflicting self-harm

My second fursona Chakat Shade (NSFW and SFW) is also me and follows the same rules. The canon anatomy specifics for chakats, which I adhere to, can be found at The Chakat’s Den and some additional visual clarifications here].

When considering which to use, go by if the activity is better suited for a taur or a biped. If there’s no clear winner, flip a coin.