The paving blocks or bricks should be laid directly onto a bed of coarse, grit sand, 25-40mm thick. This sand may also be known as sharp sand, concreting sand, Zone 2 or Class M - see the Sand section of the Aggregates page for a fuller explanation of these terms.
If it is possible pressure washing should be avoided as it is likely to damage the jointing between the blocks. Unfortunately a badly neglected block paved driveway can only be restored using power washing, once the driveway is dry then kiln dried sand should be compressed back into the foundation with a vibrating plate by a professional.
With block paving, jet washing will wash out a lot of the dried sand/cement in the joints, so re-sanding will be required. In any event, the joints of block paved driveways will need some re-sanding regularly to prevent the blocks themselves being eroded by rain, snow, frost etc.
After that I broke out my hose and misted the entire area per the directions (being sure to get everything wet without going overboard and washing things out). In retrospect I wish I had blown or swept out a smidge more sand before wetting things down so that the "seams" of sand between the pavers were a tiny bit thinner.