Well, I don't know if you'll find this super duper helpful, but if you are having trouble with a big fight, use a used diaper on the enemy. They will flee in terror and will no longer attack you (I did this to a dragon, ha!) Don't use it on NPCs, though. It kinda...breaks their mind.
You can even use clean diapers on the babies in castle British's nursery to 'reload'.
There are quite a few diapers near Locke Lake you can use as well. And as Paulon said, you can use potions on enemies/NPCs as well. Say you wanna assassinate someone but not get caught by guards....just use several poison potions( I also use the Poison spell, works just as well and the guards don't get mad). Every time one wears off, use another one. Keep in mind, this doesn't work for all characters. I.E., Lord British.
If any of your party dies, bring their body to Lord British and he will raise them for free. You can do this with named NPCs as well, if for some reason they accidentally die. For example, that's how I...rob the bank. Poison Cynthia, filch the keys from her body, rob the bank at night (either sleep the guards or use a invisibility potion/spell) then bring her corpse to Lord British. Then go back to the treasury during the day and exchange it all.
I feel I should also warn you not to keep important items on any party member other than yourself, such as the Orb of Moons or pocketwatch. If your party member becomes critically injured, they WILL flee in terror and will drop items in the process (I'm Looking at YOU, Shamino!).