There are some good answers about trails that I am not going to expand on.
For roads that are not heavily used like logging roads These may extend many miles into the forest, with multiple branches, all ending in dead ends. There can be 10's or 100s of miles (or kilometers) of roads. Often there will be a locked gate at the entrance to these areas, preventing vehicle access except during active logging.
As mentioned in answers about trails, downhill is a good choice, but roads may cross many valleys or travel long distances in them, so downhill may not help on roads.
Decisions are mostly made at intersections. The most travelled road is usually evident from the width (wider) and lack of vegetation. At "Y" intersections normally you want to choose the base of the "Y", traffic tends to enter and exit from a single main road. Logging roads are built one segment at a time over decades, they have cut offs to different directions, with the major traffic flow expected to coming from or going to the main road.
There may be power or pipe lines crossing the road you are travelling. These can seem like a short cut, but if they show little traffic compared to the road you are on, avoid them. These routes often include areas impassable by foot or vehicle, maintenance is conducted by accessing from different side of the impassable area. If it was really the shortest point to nearby civilization there would be more traffic.
Related: What is the longest dead end road on US public land?
P.S. There may be multiple locked gates. When you come to one, keep walking, there may well be another locked gate farther on towards the main road.