3D Systems posted some good tips.
My own tip is if you need a tapped hole in the printed part, model a hole that is smaller than the tap drill size. Tap the thread after you receive the part. Sending the part to be printed with the thread usually does not result with a good thread because of shrinkage/expansion and tolerance.
Thumbnails not showing? Here is a fix that worked for me (Windows 7).
1. Click the Start Button, then in the “Start Search” box type CMD but DO NOT press Enter yet.
2. In the list above, under “Programs” right-click on CMD that appears above and choose “Run as Administrator” and click “Continue”.
3. Select Yes in the popup window.
4. Type regsvr32 sldthumbnailprovider.dll5. If this line alone doesn’t work, you have to go to the folder then run it.
5. To get to the folder: Type cd\, then type cd\program files\solidworks corp\solidworks (2).
6. It will notify you that it was successful. Type Exit.