If it's the front F/W hub you're talking about, then the answer is "not a lot".
The spoke holes in the hub point to the relevant dimple on the rim, so provided you're got the right spokes (CWC are good) and can tell that a spoke is being forced/bent into position (and so is in wrong spoke hole on the rim) you can't go wrong.
There's lots of hints and tips on the Net and take drawings, measurements of off-sets and digital pics before stripping.