Muddiness almost always traces back to a buildup in the low-mid range, even when the actual complaint is vaguer, like "it just sounds unclear."
Start by cutting the 500Hz band a few dB — that single move resolves more "muddy" complaints than any other adjustment. If clarity is still lacking after that, a small boost around 2.5kHz usually finishes the job.
It's tempting to boost the highs to add "clarity," but cutting the frequencies causing congestion usually works better than piling more on top. Try the low-mid cut first before reaching for any boost.