I only allow fast travel between the different reaches because I simply don't have the time to walk everywhere, and also permadeath on adept or lower difficulties.
My general rules: No fast traveling (unless it's by carriage), eat food and drink water, sleep most every night, do not use wait function, cover up as best as possible when in cold, and don't fall in freezing water (I force myself to restart).
Sleep every night/day, eat twice a day. If I use a follower, I provide them with suitable quality armor, often enchanted. I also pay them after a difficult job is completed. I heal them when they are injured, and when I ask them to leave my service I give them the armor/weapons with which I originally equipped them. I also feed them. I will sometimes let a favorite shop owner get by with paying slightly less for items, especially if it's someone I like. Never Belethor!
I'm playing on adept because I'm a big chicken and I hate it when my character dies.
My assassin sucks in the art of magic, so when I restrict him to basic spells like healing where I will often make the spell flicker on and off in his hand to show how terrible he is. I mainly assassinate targets at night, try my best to dodge and evade attack rather than magically tanking them (I only wear shrouded robes) I buy a new daggers and bows every now and again to replace my worn out ones. Before I kill someone I enchant a item with their name then put it on their body for use in the afterlife. Eat/sleep etc. When I'm with a follower I give them food, pay them a share of what I earned since they helped me. Buy them a new weapon & rp them in a faction (example Sven is a thieves guild member stationed in riverwood). And more but I don't want to get carried away. Oh and I never use any weapons outside of daggers or bows.
http://skyrimforum.com/threads/immortal-words-saurano-direnni.13882/
BIGwooly's an expert on how to implement these kinds of rules into an interesting and creative playthrough, then provide us with one of the best character journals I've seen. His current project forces him to change characters on a rolling dead-is-dead type of format, it's very original and I recommend his other stuff, too.
Absolutely no exploiting the game. Also, Freya uses no weaponry. On expert difficulty.
The only rule I use is no exploits or cheats. Having a sword that can do 9000 damage or getting my level over 100 is a no go for me. I get no satisfaction at all from being a zero magicka cost spell-spammer or a warrior that can one hit dragons. It's a lame ass borefest and people who play like that might as well just turn on fluffing god mode and get it over with already.
Heh.... try fighting a legendary dragon with just damaging shouts like I have.... true battle of the tongues there....