From Bowman's Beach, walking northwest. Bowman's has the island's largest beach car park, restrooms and a footbridge from the lot to the sand. Pay for a city parking session, walk down to the water and turn right. Within ten minutes the crowd thins; within twenty you are on your own. This is the easier option for families and the better one if you want facilities before and after.
From the pass end, walking southeast. Park at one of the lots beside Blind Pass, walk out to the water and turn left. The shell concentrations near the pass are the best on the island, so this direction front-loads the good stuff, which for some people is the wrong way round.
Which to choose. Start from Bowman's if you want the walk to be the point, from the pass if you want shells in the first ten minutes. Either way, do the outbound leg into the wind.
Tide. Go out on a falling tide. A wide, firm low-tide beach is easy walking; at high water the strip narrows, the dry sand is soft and the same distance takes half as long again.
City parking sessions transfer between city lots while the time is running, which is useful if you want to move on afterwards.