Assuming you have one or two warriors have you sharpened their weapons to the maximum? Do they have most of their points in weapon skills - accuracy, critical hits and death blows especially? Do their skills match their weapons? The weapon and shield skill is useless if you have no shield - likewise the one hand skill is useless if a shield is equipped.
Even with two mages (and act 1 spells are pathetic) I had no problem. I charged the nearest and whacked away with my best weapons - well sharpened - until it died. Then I moved on to the next. Frequently paused the game (spacebar) and took a healing potion or two as needed but there are LOTS of healing potions and they keep filling up battlefield merchant inventories so there is no need to be cheap with them.
Getting up close and personal usually is the best technique in act 1 unless you are an archer and have lucked out with a really good bow - sharpen is a master skill for act 1.
