That was just a brief description of the main methods of putting the planks on a deck. The patterns and making them look more realistic occupies almost an entire shelf of books in my library.
Planks on a ship are almost always caulked in between. The caulking on modern yachts is sometimes white, but traditionally it was done with tar. Modern warships I think have a rubberized caulking that's more to preserve the wood than to keep water from leaking below since the deck UNDER the wood on them is usually metal.
There are several ways to simulate the caulking.
The easiest way, as I said in the last post, is to just have the deck planks inked onto a sheet of plywood. It looks acceptable, but the grain and any blemishes in the wood cross over from plank to plank so it's noticeable that they aren't really individual planks.
You can also buy scribed plywood. (little grooves cut into the wood to make it look more like individual planks.). this method has the same problem as above with blemishes and grain, but usually they use clear basswood or poplar, maple or birch and so that's not a big problem.
If using the scribed wood, you can leave it like it is, or try to fill the grooves with something to simulate caulking. The biggest problem here is making sure that whatever you use, it doesn't get soaked into the plank itself and ruin the contrast. This can be done by first coating the wood with a sealer, applying the stain, graphite or other dark material, and then sanding the application off to leave the colour just in the grooves.
If making individual planks, you can actually use something to caulk between each plank. I did this on two models that I built by using black paper. the first time, I cut the paper into thin strips and glued it along the edge of each plank and at the butt ends. When the deck was finished, I cut the excess paper off with a scalpel and then sanded the deck smooth. It came out beautiful but was a LOT of work.
The second time, I put all the planks together, and then glued a sheet of black paper along the edge and then cut each plank away individually. this was difficult to get the cuts even and straight and still left the butt ends to be 'caulked'. In the long run, it wasn't much easier and the effect was identical.
Another way of applying caulking to the edges is not as dark as the paper, but a LOT easier and comes out just as good or better (depending on scale) is to rub the edge of each plank with a soft pencil. I've seen some people who used paint, but it tends to saok into the grain too much.
You can also bevel the edges of each plank, and then after assembly, lay a thin black thread into the groove between each plank. This is just about how they were done in real life. I lot of work, but quite effective. A very thin knife with the edge flattened helps.
Finally, you can just lay the planks and forget about caulking. This works best if the planks are very, very tiny so that caulking would be almost unseen anyway.
There are other methods of course, but these are some of the most common.