The Miri visitors information centre (434181; firstname.lastname@example.org; 452 Jln Melayu; 8am-6pm Mon-Fri, 9am-3pm Sat & Sun) has up-to-date bus information and timetables.
For the long-distance bus station, bus 33 leaves regularly from the local bus station (RM1.40). Buses 28 and 30 run frequently between the local bus station and the airport (RM1.80, 20 minutes) from 6am to 7pm.
Taxis from the airport run on a zoned coupon system; a cab to a central hotel costs RM18.50. Other destinations are by negotiation – the long-distance bus station is around RM10, and a taxi between Miri and Kuala Baram should cost RM20.