cranking,The car is having trouble starting up ,70 percent of the time it starts right up. the other 30 percent, it randomly won’t start its

Car wont start some times for no reason on certain days it will start with one crank of the engine,other day's it will crank and crank but wont start unless I give it a little push start I don't think it's the starter because the engine cranks, dont think its the battery because the car won't start even after a long drive giving the battery a good charge frome the alternator.thank you for your help any advise will do!
My car has an automatic transmission.