You will first encounter the Smog after receiving the MK23 handgun and leaving Curtis' "repair shop." Once you get back to the main road, a cutscene will trigger where you get a garbled transmission from Deputy Wheeler. Immediately thereafter, you're jumped by the Smog. A real pain in the ass monster. Don't even try to kill it with a melee weapon. It's way too easy to get hit. And these things are capable of dishing out some heavy damage. Instead, pull out your pistol and wait until it inhales and exposes it's lungs. That's when they're most vulnerable. About four shots will take them down on hard, 2 on normal. But aim carefully. Like all Silent Hill games, ammo is limited. And on hard, you can only carry a maximum of 15 rounds at any given time.
Creeper Reaper (10) - (Defeated 1 Swarm)
Later on in the nightmare, you will find yourself walking down a long corridor. In the center you will see a stretcher with a corpse laying on it. Approaching will trigger a cutscene that introduces you to your first Swarm. Simply strike at them with fast attack to kill them. If one manages to latch on to you, push the defense button to pull it off and kill it.
Out of Order (10) - (Defeated 1 Order member)
You first encounter these enemies when you enter the power station in Silent Hill. They're easy enough to beat with the shotgun, rifle, or pistol. One shot at close range with the shotgun will take them down. Headshots are also effective. But melee is a little more difficult. They have the ability to dodge just like Alex. So the best melee weapon to use is the ceremonial dagger. Any combo will do. Just remember to dodge when necessary.
Kaufmann's Handiwork (10) - (Found 1 Serum)
Upon first returning to Shepard's Glenn proceed forward until you trigger a cutscene where you will meet Judge Holloway. After the cutscene has ended, head east into the town hall. From the main lobby, take the door to your right. Head down the hall and again take the first door on your right. In this room you will see two tables at the far end of the room. On one of these tables is a briefcase. Inside you will find your first serum.
Health Junkie (50) - (Found all Serums)
Collect the 8 serum injectors in the game. The locations in the order you can find them are as follows: - Serum 1: The town hall after meeting the judge. - Serum 2: The bathroom of room 408 of the grand hotel. You'll need the axe to get in. - Serum 3: Doctor Fitch's office. The examination room that the nurses burst through. - Serum 4: Between fans 1 & 2 of the fan puzzle in Hell Descent. - Serum 5: Shepard's Glen Cemetery. In the locked crypt opposite the one that connects to the town hall. You need the ceremonial dagger to open it. - Serum 6: On a bench outside of the main entrance to Alchemilla Hospital in Silent Hill. - Serum 7: In the Prison in Silent Hill. After solving the wire puzzle, jump across to the cell on the Second floor. - Serum 8: Room 301 of the Lair.
The Old Gods... (100) - (.. Haven't Left This Place Complete game on HARD difficulty.)
This achievement speaks for itself. You can try to do this from the start. But I strongly suggest playing the game on normal first. Earn the UFO ending and unlock the Laser Pistol. It will be available for a hard mode run. You don't have to. But doing this makes hard mode ridiculously easy.