Aim to get the best exposure you can in-camera first. Post-processing can help refine an image, but it cannot fully recover detail that was clipped to pure white or crushed to pure black.

In-camera exposure matters because the sensor has a limited brightness range. If important areas are overexposed or underexposed, that detail may be lost permanently. Your camera’s meter helps, but it can be fooled depending on the scene, so learning exposure compensation and metering modes is useful.

Software is best for small corrections and finishing. It can improve an image that is slightly too bright or dark, but it is not a substitute for good capture.

A practical approach is to bracket exposures: take several shots at different exposure settings, for example above and below the metered exposure. Many cameras can do this automatically. That gives you a better chance of keeping detail in difficult lighting.

So: expose as well as possible when shooting, then use software for minor adjustments rather than rescue work.