Scottish Citylink runs two main routes in the Northern Highlands; one heading west from Inverness to Ullapool and the other up the east coast to Scrabster (via Dornoch, Wick, and Thurso). It also has a route across the Isle of Skye to Uig. These buses can be a good way to see the region, but they don't run frequently.
Once you're in the Northern Highlands, Stagecoach has some routes up the east coast of the mainland to Brora. It also has regular services on Skye. In the Outer Hebrides, several small operators run regular routes to most towns and villages. Traveline Scotland, a handy website, provides timetables and a journey planner to help you navigate around Scotland. There's an app, too.
Scottish Citylink. Highland. 0871/266–3333; www.citylink.co.uk.
Stagecoach. Highland. 01463/233371; www.stagecoachbus.com.
Traveline Scotland. Highland. 0871/200–2233; www.travelinescotland.com.