A couple of our newer people seem to be having trouble using their characters fully. Mummy's Mask was designed to be beaten by 4 players. So I thought we could post a couple of pointers here. Anybody can feel free to add thoughts as well.
Firstly spell casters, which right now is Farside and TC, your primary role in combat is to make the heavy hitters jobs easy. Select spells and extracts that will either do AOE and hit multiple targets, help you or your party bypass DR and SR, or halt the biggest baddie for a round or two. Most spell casters gauge their success based on how much damage they prevented the enemy from doing. Though I will admit its been tough on TC going up against so many opponents that aren't prone to the witches bread and butter of just putting them to sleep. Chill touch, ear piercing scream, and frostbite are a few spells that you'll want at least one of prepared just for immune to sleep hex baddies.
Know your traits, so far you've seen a lot of undead and constructs and they have specific traits. Undead are always immune to mind-affecting and death affecting (including sleep, disease, poison, and paralysis) and are not subject to any ability drain (ie draining Str, Dex, Int). Constructs are also immune to mind-affecting and death affecting, and have immunity to bleed.
So how to beat them? Undead have no CON at all, their health and Fort Save is based on CHA which is almost always low. Grognak's swing past the DR is a great strategy against most undead, but brings up the point of DR. DR is resistance against everything except the listed thing in most cases. Low level DR's tend to need either Bludgeoning, Piercing, or Slashing; higher level DR's need Silver, Cold Iron, or Adamantine. So as a party prepare for all 6 DR's. For most creatures an appropriate DC 15 knowledge check is enough to learn their DR's. As a general rule fleshy undead like zombies need things cut off of them (slashing) and boney undead like skelingtons need to be bludgeoned into millions of pieces.
Constructs have a wider range of DR's, the ones you've faced so far have needed, Cold Iron, Adamantine, and Fire to kill them quickly. So the knowledge checks are much more important to learn that. Think of a construct as an ancient computer, it has a specific set of instructions on when and how to attack, a construct guarding something won't attack until a parameter is met. Either opening a door, or touching a specific item, or getting to close tends to set them off. On top of that they don't tend to give chase or pursue much, so run away, regroup and get a plan together. Constructs also have crap for saves, so any magic that they aren't immune to they will have trouble staving off (though some of them have SR).
Healing, healing in combat is generally frowned upon but sometimes necessary. A wand of cure light is considered the best healing method throughout all levels of the game because its cheap. A wand should be used before spells and extracts unless you know that you aren't facing any more baddies. Saving spells and extracts for use against a tough baddie can be the difference between success and failure.