The first thing im going to do is Rest every night, as far as the plot allows. This isnt really a restriction, but it seems to be good RP to want to rest each night. In previous games I would always delay resting as much as possible, until spellbooks are almost empty, or fatigue sets in.
Inventory:
One plan is to go without Bags of Holding completely. Scroll cases would still be allowed, but getting rid of the bags seems a good way to restrict some *very* tempting exploits, aswell as indirectly limiting the abundance of available cash.
No inventory screen during battle (I loved the 'Unpause' in BG1). No more sifting through a bottomless bag of holding for that non-magical sword to hit a protected mage. No more swapping in the Ring of Fire Protection, the instant before the fireball hits me.
Stealing:
Plundering things from merchants is fun at first, but it can kill off some of the challenge later. I was thinking of limiting shoplifting to scrolls *only*. Certainly no mace+2s. Pickpocketing is OK (very hard to leave Ribald's shop without that ring), but no save/loads allowed. To guarantee success costs usually 3-4 potions of thievery, because i dont put any points in the thieving skill.
Items:
Cloak of Cheese is out. I usually keep it in Bag of Holding and equip only seldomly. Next game I'll just leave it in the Sahaugin City. All loots from the mods I will either use or leave behind, ie NO SELLING that stuff. Item upgrade mod is fun, but certain obvious ones are banned. (The scimitar is way overpowered, improved kithix also, and others). Even in my last game, I did without Boots of Speed. The game is better without those.
Scrolls:
A nice rule here bans projects and simuls from using scrolls for spells that they could not have memorised. If mage isnt levelled-up enough to memorise Time Stop, then her Project is not allowed to use a Time Stop scroll. Once mage hits level 18, she is free to memorise any level 9 spell, and the Project is free to use Time Stop scroll.
Mage will have to reach appropriate level for her Simuls to *have memorised* black blade of disaster, before her simuls are allowed to use that scroll from quick item slot.
Smite:
I loved this ability, and although i didnt find it cheesy, it was maybe too overpowered for me. Example fight: the tough party that spawns as you open the final seal in Watcher's Keep. No reloads for me there, because the 2 nastiest enemies were smited off the screen at the very start. This still left a lot to do, but relatively little danger in doing it. GWAs need a limit of 2 per day. I would say 1 per day, but i think you need 2 at the last fight in ToB
Wearing Protection Items:
There is a mod that allows you to equip various items together (rings / amulets of protection etc) which you couldnt in the Vanilla game. I regret using that mod- the game was BETTER when you had to think more carefully about which to equip. When Jaheira breezed to -18AC or so, I realised this mod had to go for the next game.
Ranged Weapons:
My last game was a full party of 6, and no ranged weapons allowed throughout. When i got to high levels, I did use energy blades... these were amazing, but simply reminded me of why I had banned all ranged weapons. Perhaps I will reconsider this for the next game, as I wont be allowed to steal infinite bolts of biting etc. Generally I think ranged weapons are for wimps.
Carsomyr:
I think next game will be better without this sword of dispelling. After just completing the game with PC inquisitor, its already going to be really hard next time thru to fill in for the various dispells and truesights he cast so quickly. Getting rid of this sword from my game - I hope - will allow for more balanced magical battles.
Im hoping to make it more of a challenge, without increasing the frustration too much. Im very excited about the 'no bag of holding rule' (seen that on this forum somewhere i think) and I welcome the tough decisions about what to carry or not to carry, as a result.
If anyone has more suggestions for self-imposed restrictions, please post your ideas. I wont be starting new game for a little while, and when I do it will likely be my last game of BG2+ToB. I want to make it just right