Be sure to go to church everyday to donate and get great buffs. Get there at 5 am and the buffs last all day until 5 the next day. The magnitude is strongest the later it is in the week so Tensday is the best day to be there. The days also affect how much to donate; once on Onseday, twice on Twosday, increasing until Tensday at ten donations, and that's all at once right when you get there after 5 am. These buffs will save you from terrible magic and allow to kill many things using few strikes. Use the snake mirrors to get around quickly. Just type in the name of a town or even dungeons, e.g. Red Dwarf Range. Movement and attacks on the world map take ten minutes, while inside dungeons and towns they only take one minute. Cheers!
I don't remember how strong this effect is (mainly because I tend not to use it), but at sufficiently high levels, you're better off casting the spells (Day of Protection/Sorcery) yourself. Eventually, the best strategy is to give all the levels you get to one character (preferably a Barbarian) and have them use items to cast the spells (don't forget the Recharge Item spell exists).
Also, note that, at levels less than 200, Protection from Elements gives more protection against that then Day of Protection (cast Day of Protection first).
Another thing: There are fountains that can boost your stats; make use of them. This is especially true if you find a fountain that boosts the Level stat. They, again, last until 5 am or you rest, whichever comes first. Boost your level *before* you cast Day of Protection/Sorcery.