The useful first step at Harry Reid International Airport is to treat the airport's own transportation page as the source of truth. After baggage claim, follow current rental-car signs and keep the destination---Harry Reid Rent-A-Car Center shuttle---in view rather than navigating to an unrelated public address.
At LAS, follow the airport's current rental-car shuttle signs from the terminal to the consolidated Rent-A-Car Center. Check the airport transportation page for the current pickup pattern and keep the agency's return instructions available before leaving the facility.
Before leaving the facility, confirm the agency's current hours, identification and payment requirements, vehicle notes, and return instructions. Photograph the vehicle condition and keep the official airport and agency pages available for the trip home.