Car dont start sometimes?

Not quite enuf info.When it doesn't start,is it dead?If so--turn off the ignition(key) and try to wiggle the wires on the battery.If you can,they are the problem.You prob. have a "sidepost" battery,and they are bad about being loose.Also--follow these wires and check the other end for tightmness.Electrical connections should be cleaned and a corrosion--inhibitive stuff put on.Vaseline works in a pinch.---Check for loose wires around the alternator as well-------Starter next.