From ghy you may book your ticket by going towards Paltan Bazar(ADjacent to GHY Use the FOB by coming out of PF 1 and taking right ) Then you may check out the vacant seats in BUS. Best Day services are Green Valley, Network travels(450), If you happen to miss the day service try for night bus, Best service is Volvo, but you'll hardly find ticket in it. Other good services include Blue hills Night Rider(Semi Sleeper)(470), Deep, Network AC/Non-AC(550/450). If you happen to miss the bus for itanagar you may try with North Lakhimpur bus, they set out late and leave the bus at Banderdewa, From there you'll get several vehicle for Naharlagun/Itanagar