First “solo” impulsive leisure trip advice?

Im a young guy living in the midwest of usa and recently got a new job where i only work three 12’s a week, and an alternating weekly schedule. I have 5 days off every other work week .

I decided I want to travel to NYC because i know a gal who lives near the city and exploring nyc been an experience i wanted for a while. Id be aiming for staying 3 days probably.

However i feel like i know almost nothing about traveling like planning and such or how close i can book a trip out (would later in the month or next month be feasible?)
Im KINDA SORTA familiar with air travel cuz i worked in an airport for a brief moment and traveled for work in the past, but never really bought or sorted anything myself for travel or lodging.

I kinda wrote this out and realize i didn’t really make a question so:
What sorta advice would you have for someone wanting to travel solo and impulsively for the first time?