The color blue always evokes water. Blue is the most expected color, at least in the West.
Some shades of blue, such as navy and denim, function as neutrals in the wardrobe. Denim blue looks good on almost everyone, so does navy. Yet blue itself is not a true neutral - nothing differentiates cornflower or cobalt except for saturation, and no one would call those colors neutral!
Blue is a tricky color to match. Have you ever heard the words, "Everything matches navy... except navy"? True words. Turquoise is just the same, to my sadness (and yours, if you could only see the number of turquoise things in my wardrobe). It's all in the amount of secondary colors in the blue - whether yellow, in the case of turquoise, or grey, in the case of navy. And this is the reason that we don't wear denim with denim - it just doesn't quite work most of the time. The slight mottling that the denim washes produce only bring this attribute to the forefront.
It's generally a better idea to wear blues together that are far apart on the spectrum. A light blue with a dark is a classic combination. Bright blues usually look best with other colors rather than more blue. Blue and red is the color combination of politicians. Want to be someone comfortable for men to talk to? Take Edith Head's advice and wear a quiet shade of blue with white accessories.
Like grey, when you hear all this quiet advice about blue, it's tempting to put it to the side. The modern psyche wants excitement, daring, not safe. Yet blue is one of the most useful tools in your utility box. It makes a great platform for the edgier colors - imagine a nice blue skirt and a yellow blouse, for example - or wear something really extreme, such as magenta, with navy. Navy blue makes a great black substitute, and wearing blue when people are expecting black is always fun. When you have a "safe" color like blue, or a "safe" color combination, you can reach further out on the stylistic tree branch without falling off. Blue is not always safe! Consider sapphire or cobalt or turquoise - none of which can be called quiet.
Blue wears well in most fabrics. It, again, can really shine with a quality fabric - and is one of the shades where you have to consider fabric content when matching, as well as saturation and hue. When in doubt, it's better to move your to-be-matched farther apart rather than closer together - satin and wool rather than linen and cotton, for instance. (I am aching to do my fabric posts, can you tell?)
Blue is water, blue is safe and comfortable... it is not a neutral, but it plays like one. BLUE! :)