Assuming the starter engages and your headlights come on, the first thing to check would be the fuses and then the fuel pump relay. Is it clicking when you turn the key on? When was the last time you resoldered the relay? After that, then you do the spark plug test to tell if the problem is ignition-related or fuel-related. Once you determine that, you go from there.

Even though you have '78 you can go to the FAQ list for 700-900 to get instructions on how to test for spark, and a good testing sequence to figure out what your problem is. Just don't go replacing things on a guess, it's more fun to play the slots in Vegas....