1) Check for Spark at the Plugs
2) If None Check for Spark at the Cap
3) if have spark at cap remove cap and check for carbon tracking, corroded tips or a crack. If tips corroded clean and also clean end of rotor button. Replace cap and try starting if vehicle starts replace cap and rotor.
If above all checks out.
Check for fuel.
If fuel injected listen for fuel pump when turn key to on position should run for about 2 seconds. If hear pump check fuel pressure.
If carboratated take breather off while looking into carb slowly open throttle and look for fuel spraying.