So, we started playing dungeon crawls in '81 Basic D&D using roll20. For this i needed some dungeon maps. I picked up some one-page dungeons and converted them using RobA's dungeon script in GIMP. I attached an example from Dyson's delve, level 1.

But now i would need some advice, as i am not really experienced in GIMP, or in mapping in general.

Is there some tutorial how to add objects/elements to dungeons fast? Or is the only method manually adding them from my gathered objects?

Also, as you can see on this attached map, i actually create several "maps" for the different parts (on different layers), but the transitions are not very smooth, so if someone could give me an advice how to make that nicer, that would be nice.

And in general, i welcome any suggestion, opinion about this.