At Home: You may only use the bathroom when holding someone else's hand. If that person knows about this rule, you must also maintain eye contact the whole time.

How about you make each other a tack bra, 12 tacks each cup and padlockable at the back, You each keep the other's keys and if either wants time out it costs her 12 strokes of a tawse.

Drawing inspiration from your BDSM tests, I suggest this one:

Each morning, Katrina will present herself to Tori, fully naked. K's gonna drop on her knees, hand T a sharpie, and humbly ask to be marked, as her housemate will deem appropriate. T's gonna write a word or a phrase on K's body: she can experiment with content (be degrading or just silly, as she prefers) and with body parts (provided they remain covered by clothes). K then is going to sincerely thank T, "for taking time and effort to decorate this useless body", or something to that effect. K won't be permitted to wash away the body writing until evening.

Bonus level: At college, T will try to sneak the word she wrote on K that morning into as much conversations with other people as she can. Let's see how much she can make K blush...

Let me know if this is the kind of rules you're looking for, and I may come up with more... Have fun!

Rule: can’t make eye contact with others of the sex you are attracted to
Rule: must get permission to cum
Rule: May not use the first person when talking, must use third person (this one, this slut, etc.)
Rule: Must write one humiliating word on body each day
Rule: when doing laundry you may not wear clothes (if in public wear a towel, lingerie, small swim suit, just panties, or something else skimpy)
Rule: Each of you will give the other a person they must have sex with each month, failure to do so will result in a humiliating dare
Rule: one spank for each point you are off of 100 for any tests, quizzes, and homework
Rule: must study with a vibrator inserted that the other controls
Rule: must perform one day per (day/week)

Great, would really like to have an update on that, every now and then...

Update
 

a rule can be :
each morning, you flip a coin twice. head you / tail Tori
one for the bra
one for the pantie

Too bad I see you didn’t go with one of the masturbation competition options, those looked fun. And who will be giving permission to cum and perfoming the spankings? Will you be doing that for each other? Here are some rules for you both to consider, add any you’re willing to:

• You must sleep naked
• You must both sleep in the same bed
• You must shower together
• You must wear a crotch rope to at least 1 class each day
• You must leave your sex toys in plain view in the main room of your apartment at all times

I also see that Tori has no rules that only she is following. I think we need at least 1 or 2 specific to her, so here are some ideas that might fit her:

• Tori must grab Kat’s butt at least once each day
• Every time Kat has sex and Tori’s not part of it, Tori must masturbate for at least as long as Kat spent fucking. She must start as soon as possible after learning that Kat is getting/has gotten laid.
• Tori may not wear any outfit that’s less revealing than what Kat’s wearing that day
• Katrina will give Tori a person that she must kiss each month, failure to do so will result in a mildly humiliating dare.

If Tori doesn’t want to do these all the time, consider having them only apply on certain days. And I suggest a punishment if she doesn’t follow a rule she’s agreed to: The next day, Kat will pick one of her rules and make Tori follow it instead of her (pick a rule that’s within Tori’s limits of course:)).