I just bought a tahoe and it runs great. But if it sits for awhile it's hard to get it started. Any Ideas?

Thank you

Hard to start, as in a strong crank but no start and need to repeat several times, or hard start as in slow crank and eventually need to boost the battery with jumper cables or battery pack then it starts. How does it run after it is started? When was the Fuel Filter last changed, when was its last FULL tune up? What is "awhile"? Overnight or several days/months. Cold outside or mild? need more info.

Kt