I usually keep my mini pet in one of the hidden bags so that I don't accidently sell it to the merch. But the side affect of this is that I usually forget to bring him out, especially in Canthan missions where time is of the essence and you start going at the very beginning.
Would like to see a way to "equip" a mini pet from your I screen. Have a slot, like the one for weapon and shield/offhand where you just slot in a mini pet. The pet will automatically come out when you leave a town. If you don't want the pet to come out, move him out of the slot into one of your bags.
They can't be sold to merchants so you don't have to worry about selling them accidentally. I use mine as a bag space seperator, so i dont accidentally sell things I want to keep on me if I overclick the sell button... I've lost way too many greens that way
I like using mini pets as seperators for stuff like one person said, I just sell mercilessly and everything past the mini like ID, salvage, scrolls, weapons, w/e get saved