If you check out the wilderness tag I added to yesterday's post about the sketchbox dice tool, you will notice that I was once working on some tricks for designing landscapes at or around the one page = 2 leagues level. I called these "SubHexCrawl tools", because they were intended for generation of details at a scale between dungeoncrawl scale (for interiors, villages or ruins) and hexcrawl scale (for wilderness or long-distance travel.) One of the things that happened was that I promised the next part of that series was going to be about paths of various kinds: roads, rivers, streams, walls, anything that is basically linear but that changes direction.
I didn't finish it because I had a couple competing ideas on how to do this, and neither one seemed completely satisfactory as a quick, simple method, nor did either look significantly better than the other. And then other topics became interesting, so I set the idea aside. But now, I have to go back and do this, since it's relevant to creating maps for a sketchbox campaign: when you draw roads or rivers that connect your towns and villages, you need to use the same techniques.
Let's start with what we already know: the basic direction and distance to the next settlement. You could just draw a straight line on your map to the next settlement, maybe make it curve or snake a bit if it's intended to be a river. That's pretty dull, though, and will lack a bit of realism, so we'll only use that as a starting point.
Both roads and rivers are going to be affected by terrain, so you will either need to know where your hills and hollows are, or you will need to establish them by rolling d4s for elevation changes. Roads will tend to stay on lower elevations and not go straight over hills, going around instead; they won't necessarily go down in every pit or hollow, though, but might go into a depression with a shallow slope. Rivers will definitely flow into lower levels, forming ponds in some cases; if you need to continue further downstream but can't because everything is at a higher elevation, cut a canyon through the hill or plateau.
Vegetation or other features probably won't matter too much, but if you have a clump of dense brush or woods, roads will tend to go around those, too. In those cases, you might want to roll for placement of a layer.
Roads will also tend to go around landmarks, or between them if you have a group of objects. You should place or roll for all landmarks between your two endpoints of your road. One roll for every league would work best. If your landmarks are of the constructed variety (the old church, the ruined tower,) roads will go towards the landmark first, then go around or turn away from it. So will rivers, although that seems unrealistic (people don't build rivers!) What is really being emulated is the fact that a constructed landmark would have been built near the river, so the river must have flowed close by, at least at one time.
If you aren't quite mapping out all the little twists and turns yet, but just need the general gist of the road or river for a player map, use the sketchmap dice tool to plot the path's shape. Roll 1 die on the map for each league between the two settlements; each die represents a point in the path where the path turns or splits, with some kind of terrain feature or landmark at that point. Connect two dice in the same hexagonal ring in numeric order, with ties representing forked paths.
If two dice with the same numeric value are close together, the path splits and then rejoins; put some interesting feature along each path, if it's a road, or put something between the paths, if it's a river or stream.
If two dice with the same numeric value are farther apart, only one of the two leads to the next settlement. The other is an offshoot path, leading to some other feature.
Direction matters. The dice furthest from the center represent the final stretch of the path to the destination. If these are in the opposite direction from the destination, the path is going to have to curve back around; there needs to be some terrain feature blocking a more direct route.