Blue has a reputation for being the safe choice, the colour you reach for when you can't decide, and I think that undersells it. A true blue top can look sharper and more deliberate than black if you get the shade right, though I spent a good few years assuming any blue would do and ending up with tops that made me look washed out by lunchtime.
The main thing to watch is what you put blue next to. Navy and bright blue together can look like you got dressed in the dark, even though they're the same family, so keep the rest of the outfit in neutrals, white, camel, grey, or let a second colour do a small job rather than compete. Denim is the trickier pairing than people expect, a cornflower or cobalt top over blue jeans can go a bit matchy in a way that photographs worse than it feels standing in the mirror, so I usually go a shade or two apart if I'm wearing both. On fit, blue tops in a lighter weight fabric show every pull and gape more than a patterned top would, because there's nothing to distract the eye, so if a button front gapes at the bust or the fabric strains across the back, you'll see it immediately rather than it hiding in a print. Go up a size before you go up in effort trying to make a too small one work, and check the shoulder seam sits where your shoulder actually ends, not an inch in, because that's the detail that makes a top look bought rather than borrowed. Sleeves are worth a proper arm raise in the changing room too, a lot of blue cotton tops are woven tighter than you'd think and will bind under the arm the moment you reach for something on a shelf.
A mid blue or chambray tone works through most of the year and most occasions, it reads smart enough for work under a blazer and relaxed enough for a weekend lunch, whereas a true bright blue feels more like a summer colour, something for daylight rather than evening. Deep navy is the one that behaves most like a neutral and is the easiest to build an outfit around without much thought, while pale powder blue is lovely against most skin tones but shows marks fast, so I'd save it for days you're not going to be near red wine or small children with sticky hands. If you're buying one blue top to actually rely on, a mid tone with a bit of texture, like a brushed cotton or a soft knit, hides more and worries less than anything too shiny or too pale.
Wash darker blues inside out and on a cool cycle, since that's what keeps them from fading patchy around the collar and underarms before anything else wears out.