Even though electricity is dangerous and only a ...

If you follow your own cautions in your question you should be just fine.

Make sure your replacement switch does not have any special requirements.

Replacing a light switch is fairly straightforward, but you need to take great care as you are dealing with electricity which can be dangerous.            
Make sure you turn the power off to the light switch at your consumer unit.
Unscrew the two retaining screws on the switch and pull away the switch.
Tip If it's an old switch that has been painted around many times over the years a good idea is to score round it with a sharp knife. This stops you pulling away the paint work on the walls.
Check that there is no live with your voltage checker, having previously checked that the voltage checker is actually working.

Hi,

   Always make sure the power is SHUT OFF by turning off the breaker in the circuit breaker box or by removing a fuse in a fusebox. Note: fuseboxes are not as common as circuit breaker boxes.
    Test the switch. Make sure the light switch does not activate a lamp or other electrical device.
there are Single Pole Switches and there are 3 way switches
You need to determine which kind you are replacing. A single pole switch has only 2 wires going to it (excluding any ground wire. A 3 way switch has 3 wires going to it.
Pay attention to each screw and remember what color wire goes to each.