The cheap and cheerful rule of thumb.
Try not to wear all of your bargain basics all at once. The general rule is that cheap pants in bright colours usually look cheap. But a cheap pair in a neutral colour generally look more expensive. An example is that a cheap white tee will do fabulous with a tailored skirt or pants. Or the basic footless black tights will go great with a fabulous print dress and black flats. A simple, classic but chic look.