Hi

I can't really talk about kingdom borders, but I can talk a bit about roads. Simplest way you can keep consistent with how your roads look, is choosing a hard round brush, UP the spacing and just draw the line of where the main roads go. This works well for keeping the spacing between the dots even. Then on road placement: For that I would probably spend some time identifying towns, cities and ports. Because that helps in making informed decisions about where the population would most likely set up travel and more importantly trade routes.
Another thing to take in consideration, if there is going to be dense forests, the likelihood of people going around is higher, same goes for a desert, unless there is consistent places to find water throughout, that might encourage a trade route to take a calculated risk through a desert.
A nice question to ask is, why would people to choose to travel a certain path more often? Nature has a way to influence decisions. Hope that helps.

One thing I want to touch on besides the roads, are the rivers.
Rivers goes from the highest point where it starts to the lowest point, which is most of the time the sea, or basin where a lake then forms. One thing rivers RARELY do is split. It is super common for rivers to flow INTO each other, yes, but splitting requires very rare conditions. Deltas is an exception, with the land flattening out and the water finding winding paths to the sea.
Just something to keep in mind. (It is helpful to look at Google Satellite images of rivers.

Good luck with your map.