My guides tend to be straight forward. I will simply show you the fastest way to get 100% Achievements.
If you don't want to rob yourself of the fun you could have with this game, move along.

Descripton: Oops.

Walk forward from where the game starts towards the dog. It will "attack" you and you will drop your camera which grants the achievement.

Description: Met your first real brujo, Don Miguel.

After meeting the dog turn right and follow the road until you see two men. The one who is standing in front of the building to the right is Don Miguel. I think the achievement popped when I took a picture of him.

Description: Your camera is no longer a passive observer.

After taking the taxi ("Take me somewhere far") walk across the soccer field and take a picture of the little boy with the ball who is standing in front of the house.

After getting out of the Taxi:

The soccer field:

The boy:

Description: Making friends with your camera.

After leaving the soccer field go left and follow the road until you get to those two guys in the screenshot. Simply take a picture of them.

Description: Photo-mediated chiromancy.

After completing "No Manners" turn left. There is a woman standing in front of a red house. Walk up to her and take a picture. She will hold her hand into the camera to stop you from taking a picture of her. Turn left again and you will see Don Miguel. Show him the picture you took of the womans hand.
The woman after you took a picture of her (house gets destroyed in the process):


The guy you gotta show the picture you took to:


If the Achievement doesn't unlock right away, try taking several pictures of the woman's hand and showing them to Don Miguel. Her animation will repeat every few seconds so you might have to try several times.
The right moment to take the picture is when she has her arm up and spreads her fingers.

Description: Final trip.
When you're visiting the "Casa del Diabolo" go up to the house, take some pictures and when you try to get back to the taxi it will drive away. Go back up to the house and the final scene will play.

Since this achievement wasn't explained properly I add some more information on how to get it.
After meeting the two people from the "No Manners"-Achievement keep following the road to their right until the very end. When you turn around the taxi will be waiting behind you.
Get in and choose "Is there a lake somewhere?".
After that get back into the taxi and choose "I think I want the San Pedro lagoon".
After you've been there get back in the Taxi one last time and tell the driver "Is la Case del Diablo far?" and he will take you there.