You will need insulated, pointed, electricity pliers, a screwdriver, a sharp knife and good quality electric tape. The first and most important step to take is to turn the electric power off to the area or switch you will be changing. Turn the light on, now go to the electric panel and throw the breaker switch to which the lamp is attached. If they are not labeled properly, turn them off one by one checking if the light went off inside. When it goes off, you have found the right breaker switch. If you do not want to do this, throw all the circuit breakers off.
Now using the screwdriver, remove the screws attaching the switch to the electric box in the wall. Pull it out and take a good look at all the wires screwed to the sides of the switch. They should have different colors for proper identification, if they don’t you can still do the job, do not worry. Compare the screws of the new switch to those of the old switch, make sure they are located in the same place and that there is the same number of screws. They will all be the same color with the exception of the ground screw which will be green.
Here I will take a break from the process and explain a little something which is very important. If you are changing a light switch that is the only one used to turn a lamp on and off, any switch will do. When the lamp can be turned on from two or more switches located in different areas of the room, a special switch is needed. If this is the case make sure you tell this to the attendant at the hardware store so he sells you the right kind of switch. This is no big deal; they are just different and have an extra wire connection.
Okay, back to work, the electricity is off and the switch is off the wall too. Take a good look at the wire distribution on the used switch identifying every wire and where it is connected. Loosen the first screw on the used switch, using the pliers take it off the holding screw. Using the pliers straighten the wire out and with the night scrape the end of it so it is shiny and clean again. Make a u shape on the tip and put it around the same screw on the new light switch. Make sure the u is tight against the screw base; tighten the screw until the wire is firmly in place. Do the same for all the other screws. Now take the electric tape and wrap the sides of the switch with a couple of turns covering the screws and the wires. This is a precaution in case that for some reason the screws touch the metal electric box in the wall.
Screw the switch tightly in place and put the cover on. Turn on the circuit breakers in the electric panel and test your new light switch. You have now become an electrician; you are now able to change any light switch in your home, free of charge on your own time. Congratulations you have mastered your fear of electrocution by switch change.