Once in Liberia do not expect formalized travel arrangements. When traveling carry a book, toilet paper and patience.
The state of public transportation is much deteriorated from 30 years ago. Where once there were many small buses zipping around the capital, now there are few. Taxis serving more like mini-buses jamb the streets joining in the traffic blockages that now regularly occur. You will see some wild driving; hopefully you will survive.
No longer is travel up country primarily the domain of pickup trucks (then called money buses) modified with seating in the back. Small yellow "taxis" go from town to town. One day one of these "taxis" will disappear in a pot hole, never to be seen again.
From the border of Cote d'Ivoire to Ganta we went with a taxi, a road through rainforests. It was a long trip, and we were not treated friendly at a roadblock near Sanniquelli. Our taxi driver Moussa drove very carefully on the road, and brought us safely in Ganta, for which we were very thankfull.
Fly via Europe to Abidjan and then fly Weasua to Monrovia. Use Air France, KLM, Sabena from the USA or Europe to Abidjan. Air Afrique also flys direct New York via Dakar to Monrovia, however the service has been off schedule as of late. Email me for Weasua's schedule between Abidjan and Monrovia: firstname.lastname@example.org
4x4 vehicle and canoe