I start by painting the entire hull the red color of your choice (Tamiya hull red). These are steps I followed to paint a USS Missouri Measure 22 colors (water line, boot topping, navy blue to the sheer line, haze gray to the deck).
Next I mask the top of the water line. If the lines aren't visible or not clear in some parts you may have to re-scribe the line using a surface gauge or some other fixed scribing tool.
I spray the boot topping black without worrying about the top edge.
Leaving the red masking in place I mask the top edge of the boot topping.
This ship needed another mask for the top edge of the Navy blue. Again, leaving all the other masks remaining on the hull.
Finally, and again leaving all existing masks in place, I mask the sheer line which is the level line where the deck begins to turn up at the bow in preparation for the haze gray.
The moment of truth when all this masking is removed. Notice, I use Tamiya narrow tape for the edges since it makes turns better, and also note that Tamiya now makes a flexible vinyl tape that conforms around curves and this ships "cruiser" stern is especially sharp.
Hope this helps.