Some color combos are traditionally a fashion faux-pas. Some fashion rules about mixing and matching colors were drilled into us since childhood - but like all rules in art, they’re meant to be broken. Few people sell wholesale blouses in clashing colors - but if you can sell these, it's a masterpiece.
I’ve read not to mix white and off-white, like cream. Well, honestly it’s a risky combination because cream mixed with pristine white looks “dirty”. The solution is to add a third color that will take the “dirty” - pink or red or gold. Then, cream will look more “pinkish” and less of a dirty. You could also try textures or unusual patterns.
Speaking of pinks, you allegedly shouldn’t mix pinks and reds. This is true, but if you have a cold skin tone, you can carefully try this combination. Tone down one color and allow the other to dominate - vivid red might go well with pastel pink, or neon pink dress with a single dark ruby stripe would rock the evening.
Brown and blacks are another fashion faux-pas, but only if the browns are dull or dark. If you switch to tans, beige or caramel, bright brown accents will beautifully distinguish themselves with black.
My mom used to say “Blue and green should never be seen”. As with pink and red, this depends on your skin tone; if your skin is “cold”, you probably should avoid this combo, but still - allowing blue accents in a green outfit could work quite well. Avoid bridging colors like teal or aquamarine. Instead, try out a dark navy blue blazer or wholesale blouses and a bright green skirt.
A nice trick to prevent colors mingling is to wear an accessory that uses both of the colors - it will be a nice transition element.
Remember, fashion is an art, and you shouldn’t be afraid to experiment. Colors are only one element of a successful outfit, and you can use textures and prints to a great effect.