My 74 just recently quit starting, what are the most common solutions?

My car does sit  lot.  I have had  Gas smell in my 74 for a while.  What are the Most common culprits?

I had gas smell in my 73 it was the diaphragm in the pump.But the pump was wet and it dripped on the floor.

Does it not start AT ALL, or do you have to crank on it for a while before it starts? If you have to crank on it a long time before it fires, then I would suspect the carb fuel bowl welch plugs are leaking, and the fuel bowl is empty after sitting for a couple of days, requiring you to crank it over for an extended time before it will start. If this is the problem, it will require removing the carb and taking the throttle plate(base) off, to repair.

If it just won't start at all, then that's a whole nuther issue, and would require more info. Like...does it spin over or not? 

Check the rubber fuel lines on the top of the fuel tank. My original fuel lines rotted out on my 74 and prevented fuel flow. They also cause a gasoline odor before failing.