Usually when a bike is hard to start, the valves need to be adjusted. On a bike of that age, the number of electrical problems from corrosion can be high. Rubber bits get stiff and crack. O rings lose their seal. Rust in the tank can block up the carbs.
Is this a new to you bike that you are trying to get running and it has been sitting previously?
or.......... Is this something that just suddenly happened and you have been riding it, then this happened out of the blue???
Start simple.......make sure the fuel tank is not rusty inside and the petcock flows
new fuel filter and carb clean
adjust the valves and do leakdown and compression checks, obviously check cam timing etc at that time
change oil and filter (is the oil level overfull like it may be full of gas in the crank...ie carb needle/seats bad)
then of course there are the associated likely issues, more important than "does it run" like; brakes, and tires and all the things that make the bike be able to perform and handle and keep you out of mortal danger.........