1.) Pick an unintimidating, simple area that you've never been to before. This morning I chose a very popular riverside loop near Beauly (see Walkhighlands description at this link here).
2.) Spend 20 minutes studying the map, picking out key junctions, obvious features to follow (in this case, the river), and thinking of any places which might be confusing. Try to commit the whole thing to memory.
3.) If you have a smartphone with a GPS app such as Viewranger or Memory Map, perhaps pop it in your bag as well (checking beforehand that you've downloaded the relevant area of map on to your phone).
4.) Get yourself to the start point of the route, treat yourself to a good look at the map and the ground, and make sure you're going to at least set off in the right direction.
5.) Now stick the map and phone in your running bag and leave it there!
I love this way of running - kind of allowing myself to get a bit lost but having a vague idea of where I'm meant to end up. There's the freedom to head down little bits of unmapped trails just because they look nice to run, unlike when you're slavishly following a route on your map. The GPS device is a bit of a security blanket in case you do get completely confused. Still, probably not a great idea to run like this up in the higher hills...