Like roach says, there is some challenge to getting the footprints just right. My personal trick has been making the holes too small - if I'm lucky the leads can be worked in, but not always.
With a little digging, you should be able to find a drawing of the suggested mounting arrangement. Follow what the manufacturer reccomends but consider making the pads extend a bit further than recommended if you'll be hand-soldering an SMD part.
Finally, after the board is laid out and the Gerbers generated, look at the Gerber files with a Gerber viewer - there are a number of free ones available. The Gerbers show what will actually get made, so this is the reality check. Check to see if what's on the board matches the recommended footprint and see if the part will actually fit!
Finally, the best-kept secret is
www.freedfm.com. Upload your files to them and in a few minutes, you'll have an e-mail indicating any problems that their system has found. Overlapping holes, layers that are a mirror-image of what they should be and other problems are quickly found.