We arrived at the airport a bit earlier than expected, and as it was our first time renting a car, we thought we would pick the car up directly at the airport. Later, we found out that, at least in San Juan, all car rental companies, including Hertz and Avis, have pick-up locations near the airport. These companies provide shuttle services to and from the airport. Big companies have shuttles that come every few minutes. However, we booked with a small company, and they came only after we called them (of course, this was because we arrived early; otherwise, they might have been waiting at the airport). Also, note that the cost of the shuttle service is not included in your booking fee. The service was excellent, and the staff patiently and thoroughly explained the terms and how to use the car. They also answered some of our travel questions and tried their best to help us. The only downside is that this company has fewer car models to choose from, with limited options. However, the car we got had only about 7000 kilometers on it, so it was very new.