Screamers make for a good meal. Mummies are dangerous, and you must hit and move in order to kill them this early on (keep in mind where you saw an altar as you'll be needing its services). A couple of things to note on battles: closed gates can be an asset, and what is dangerous to your party is also dangerous to monsters.

Recover any thrown weapons after a battle. If some are missing, a monster may have picked them up. Find and kill the offending monster to recover the missing weapons.

Do not be stopped by closed/locked doors. Where there's will, there is a way. Sound is as important as sight, so turn up the volume!

This area is simple except for one area where there are two pressure plates and an iron gate. Walk on the first plate but go around the second plate and it'll work fine. After you've retrieved the keys and finally arrived in the room with the screamers, kill them and keep going until you come to a room filled with pressure plates. Here's the correct sequence that'll allow you passage: when you step onto the first pressure plate in the room, that's the first move. From there go right 1, then forward 1, left 1, forward 1, back 1, forward one, and back one. You should see the gate come open. If you've become confused or it just didn't work, go back to beginning of the room and try again.. You'll get the hang of it. Remember to save your game every once in awhile!

Next you'll come to a trap door. Set a rock or something on the pressure plate and the trap will close up. Keep following the only way to go and you'll later on come across a wishing well. Put the coin in to open the door.