Wheels, pedals, & saddle - Check that the handlebars, wheels, pedals and saddle are secure.
Nuts & bolts - Check that all nuts and bolts are tight and none have become loose in transit.
Height adjustment - Adjust the handlebar and saddle height to suit the rider.
Tyre pressure - Use a pressure gauge to check that both tyres are inflated correctly.
Gears & brakes - Test and check that the rider knows how to operate the gears and brakes.
Stem & front wheel - Hold the front wheel between your feet and attempt to turn the handlebars to check that stem bolts are tight.