In general, avoid clipping important highlights. If bright areas are blown to pure white, that detail is usually gone and can’t be recovered from the RAW file. Slight underexposure is often safer because you can usually lift shadows somewhat in RAW processing.

That said, the real goal is to avoid losing important detail at either end. If shadows are clipped to pure black, that detail is also lost. Exposure should preserve detail where it matters most in your subject.

A small miss either way—often around 1/3 to 1/2 stop—may be recoverable. If the scene fits comfortably within your camera’s dynamic range and the histogram shows unused room on the right, you may be able to “expose to the right” to capture cleaner shadow detail, as long as you do not clip important highlights.

So the practical rule is: protect important highlights first, unless you intentionally want blown highlights for artistic reasons. Then expose as brightly as you can without clipping the parts of the image where you want detail.