I'm hoping to communicate the idea of seeing a subject in the way you need to paint it - as opposed to just seeing the stuff you're looking at. SEEING THE PASSAGE OF LIGHT, NOT ISOLATED OBJECTS.
Here's a painting by Edward Seago of the harbor in Istanbul. That's Hagia Sophia on the horizon. He probably did this from Prince Phillip's yacht - he was a favorite of the royal family and Phillip was an avid leisure painter who took him on world tours.
It's an oil but it makes a good watercolor/master copy project. I am presenting it in 4 versions to show the "layers" or sequences one needs to see to paint it. (Bear in mind it's hard to do 4 identical versions - they do differ but the idea should come across).
The palette is ultramarine, yellow ochre and alizarin or its equivalent. And yeah, I smuggled in some cobalt turquoise at the end...
The first 2 will show the lighter layers, the next 2 will show subsequent applications of darker colors - standard watercolor practice.
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Stage one is reminiscent of this Turner Venice watercolor (2 centuries back and a bit further west)
Below, I've laid a wet wash of yellow ochre in the upper right, blue in the upper left and blue+alizarin +a smidge of yellow ochre at bottom. SLOP EACH COLOR ON QUICK AND BRING THE NEXT COLOR TO, BUT NOT THROUGH, THE OTHER. THEIR WET EDGES WILL MAKE THE CONNECTION WITHOUT CREATING AN UNWANTED 3RD HUE AT THE JUNCTION. You get a kind of tie-dye triad. LET THIS DRY. You can "mask" those light spots in the harbor and boat area with a china marker or just paint around them in subsequent stages if you're feeling deft.
In stage 2 the initial "spine" of blue-grey goes over the whole land/boat mass in one continuously painted passage so that it's still damp at the end. This way you can mop/lift some steam spots at mid-right. The color is all 3 components mixed, heavier on the blue. HINT: Put in the masts and minarets first. Then pull the horizon under them and they'll melt in seamlessly. I didn't do that on the stage 2 version but did on stages 3 an 4.
In stage 3 a darker mix of the same 3 colors picks out the closer boats and structures. Mix those colors in SLIGHTLY varied proportions to enhance the illusion of space. Paint around the lighter bits (like the striped boat hulls) or lift them later. It will do so easily since ultramarine will predominate in this mix.
Stage 4 is a darker still mix of the same colors but let alizarin and yellow ochre stand out in the mix for the closest boat. This stage gives us the "telling detail". This approach favors back-lit or foggy or low light subjects but any subject has to be seen in its layers of value. Here they're more obvious. Seeing those value layers gives a sense of the light AROUND the objects. Painting them in isolation makes them look "wooden" or flat.