Mark seems that divide the object into sections to allow any continuous details to hopefully not have to cross any seems, upwrap, find the most ugly island, mark/unmark some seems you hope will fix it, repeat until you are
sick of it
Honestly Wookie is right, as you go you'll learn what shapes on a mesh are troublesome and how best to approach them through lots of experimentation.
And yeah, I love Royal's videos as a direct and to the point map of how to get something done, but I think they're most useful when you have a general idea what you need to do and need a guide to how to make it happen in Blender. He does do some teaching of concepts and such in places, but the format is best for demoing workflow I think. Besides him I have gotten a lot out of Josh Gambrell's hard surface modeling videos, and he's recently posted one on unwrapping, but he deals a lot in heavy use of booleans, making high and poly meshes for baking details, and that kind of thing, which may not be suitable to what you're doing. Hell, I've yet to finish a ship since my own recent plunge back into 3d so I'm not ever sure it's suitable to what I'm doing yet