The Sims 3 Tips

The Mini Death Guide.
There are several ways to die in Sunset Valley: burning, drowning, electrocution, starvation, and old age. Each death changes the physical appearance of the ghost.

If a sim is next to an object or surface that is on fire, they risk catching fire themselves. The On Fire moodlet kicks in with a timer below it. If the fire is not extinguished in time by another Sim or the Sim reaches a water source, the Sim dies. If the Sim makes it to water, the On Fire moodlet becomes the Singed moodlet.
Possible ages: Child, Teen, Young Adult, Adult, Elder
To Avoid: Be cautious around fire. Don’t get too close. If your Sim does catch fire, put out the flames right away.
Colour of Ghost: Red

Swimming while Fatigued is dangerous. The Fatigued moodlet has a timer beneath it and if the Sim is not out of the pool by the time it reaches zero, he or she drowns.
Possible ages: Child, Teen, Young Adult, Adult, Elder
To Avoid: When Fatigued, a Sim usually tries to get out of the pool. Allow this.
Colour of Ghost: Blue

Trying to repair broken electronics without a high enough Handiness skill risks electrocution. So does using an electrical object while standing in a puddle of water.
Possible ages: Teen, Young Adult, Adult, Elder
To Avoid: When a Sim fails to repair and electrical object, they typically get the Singed moodlet as a warning. Take heed of it. If the Sim tries to again, they get zapped to the point of death.
Colour of Ghost: Yellow.

Failure to feed a Sim after a set period initiates the Starving moodlet. There is a timer on the moodlet. If the Sim has not been fed before the timer reaches zero, he or she dies.
Possible Ages: Teen, Young Adult, Adult, Elder
To Avoid: Feed the Sim, for goodness sake.
Colour of Ghost: Purple

Old Age
Reaching the end of the life cycle.
Possible Ages: Elder
To Avoid: None.
Colour of Ghost: White