She handles this scientifically

Valerie walked over to a fruit bowl and picked up an apple, inspecting it thoughtfully.

"I wish this were an orange," she said. And it was.

She fetched a knife and cut it in half -- yep, orange. Tentatively, she touched her tongue to it, tasting orange juice. Well, that clinched it. It would've been impossible to fake that for a prank, especially since nobody could have predicted what she'd wish for.

She glanced back at the cheerleader, and any sense of rivalry drained out of her. All this time, she'd been holding herself up against Jessica, competing with Jessica, marking her progress in comparison to Jessica... and it turned out Jessica wasn't even a human. She was worth less than the least ambitious detention-hopping druggies; they were at least people, worthy of basic respect and moral consideration, and she wasn't. She was just a thing that happened to be very good at pretending to be a person, so it could do its job.

And its job was to enable Valerie's desires.

Of course, it still might have lied to her. Or not given complete information, either out of resentment or simple incompetence.

"I wish I accurately understood the basic rules and implications of this ring's wish-granting power," she said. She watched Jessica shudder with the sudden wave of stimulation, and then the information, accurate and complete, was there in her mind.

Hmm.

So this was kind of like any modern smart device. She had an object that could perform a function -- the ring -- and a kind of AI interpreter to parse her demands -- the genie. There didn't seem to be any of the usual limitations of pitfalls encountered in genie stories, unless the magic itself was lying to her... no, considering that was pointless. If it could partially disobey her wishes like that, she was screwed anyway. She'd have to assume the information she'd wished for was accurate.

First: protect her property.

"I wish this ring couldn't be removed from me against my will," she said, "I wish I couldn't be harmed against my will." Uh... what else to protect her ability to make wishes? So long as she could make wishes, she could fix any other problem. "I wish my ability to speak couldn't be impeded." Oh, and she'd better protect her access to the genie, too. "I wish Jessica couldn't be harmed against my will."

"Mistress, please," Jessica moaned through gritted teeth, "condense your wishes down to one wish and make them all at once."

Valerie glanced at the genie who was doubled over, rocking on its heels with the consecutive waves of sexual stimulation, and dismissed the request. The genie's discomfort was irrelevant, now that she knew it wasn't a person, so there was no reason to put in the effort to condense her wishes.

Okay, that was the groundwork laid. Now to get to the real work.