GPS devices and smartphones are increasingly being used for navigation in the mountains. Many devices will let you pre-plot a route using mapping software on your PC (such as Memory Map, Anquet etc.), or download a prepared route from elsewhere, such as the Walkhighlands website. The line of the pre-planned route can then be shown on the screen.
It sounds the ideal solution for finding your way safely about the hills, but it’s important to realise there are limitations to technology and that safe navigation involves the skills to read and interpret a map rather than just following an arrow. Mountain rescue teams respond to many call-outs because of GPS/smartphone failure, inappropriate route choice or because people are unable to use the technology effectively.
Use this link for advice from Mountaineering Scotland.