We have lighting fixtures and lamps that come in to our shop for repair that are simply dangerous to be have been used! Lighting fixtures are often over look when scheduling routine maintenance! Most people should rely on a qualified person to help with checking there fixtures!
There are some basic things you can check, but if you you are not sure always have a qualified person do it for you! Always unplug or turn off the circuit breaker before proceeding! Check the inside of your sockets there should be no signs of arching or corrosion! Check wiring you can see is the protective coating show sign of  waring, is it stiff and brittle, if it is it will need to be replace!There will be other things to look for depending on the type of fixture! Also never use a bulb the is not designed for your fixtures design, Such as a 250 watt bulb in a lamp that is rate up to a 150Watt or 100Watt bulb or a halogen bulb in a fixture design for incandescent bulb!