The easiest parking garage is Lee Landing at 200 South Second (just south of Beale and next to the Westin).
Exit in the elevator and take 3 lefts.
From the garage:
Go left, walk half a block past the Westin to B.B. King Drive.
Go left on B.B. King Dr., walk past the FedEx Forum and Starbucks to Beale Street.
Go left on Beale and walk half a block to A. Schwab a 163 Beale.
Also nearby at a similar distance:
250 Peabody Place Parking Garage
110 Peabody Place Parking Garage
In addition, there are street parking spaces and many surface parking lots surrounding the Beale Street district.