Hello, new mapper here. This is something that I've never figured out, should I have the walls inside the room? Or on the outside? It seems that whatever I do, everything ends up off-grid and ugly.
in or out its up to you. you may have toggled off the grid, or made the grid really small. hit Ctrl+W to enable snap to grid and the [ and ] buttons to make the grid squares larger/smaller.
These also make the grid larger or smaller. I tend to think that putting floors and ceilings along the edges of walls is easier in the long term. So, like your first picture. For sealing your map, though, you can do it either way.
Also alt+a and alt+s makes the grid smaller/larger. These are more usefull to those who don't have [ ] as a separate keys.
Yeah I put walls "inside" as well, and have the walls start on the floor. Also you may want to have the space where two walls meet be a diagonal line from the inside to the outside corner instead via vertex manipulation, so that it's more like |/_ than |_|__