Usually, fashion tips tend to be super long and super complicated.
I’m going to talk about something easy and practical: the color contrast.
Forget about color theory; it’s a bunch of bullshit. Just focus on what looks aesthetically pleasing.
The easiest colors to contrast are dark/light versions of the same basic color. Light blue and navy, for instance. If you want to get fancy, you can also get something close the light color. You could do turquoise/navy, and it would work just as well.
If you’re not sure what you’re doing, don’t look at other guys; look at women and copy what they’re doing.