I was cruising the internet today and came across this resource to share with the community. If you ever wondered how to secure those car loads and the equipment needed to do so correctly, check out this PDF file of the Alaska Railroad Load Manual. It is actually good reading on how a 1-1 railroad does their stuff for freight shipped on the railroad.
http://www.alaskarailroad.com/Portals/6/pdf/freight/Load%20Manual.pdf
Sorry I could not figure out how to make link clickable 
At one time, I used a light daub of rubber cement to secure loads. Not the “fix-it-forever” GOO but the common office variety.
I hve the DOD load mnual If you email me at igoldberg1@embarqmail.com if will send you a copy
Ira
Volume 20 of the Railroad Prototype Cyclopedia has a superb article on loading flatcars, with good illustrations of the AAR rules and a multitude of photos (including military loads which are creditd to a military man who presumably had access the rest of us would lack). The era portrayed is not exactly up to date but is probably generally close to current practice.
It is unfortunately out of print but a good train show might have book dealers that have back issues.
I also have two volumes of the circa 1950 AAR rules for open loads – that also covers gons. Those were surprisingly cheap at a train show. I had been looking for them for years ever since a Jim Hediger article in MR summarized a small part.
It is worth pointing out that AAR and railroad rules for open loads are in a sense the minimum for safe handling of the load. The shipper may and probably would take additional steps to protect the load. For example the Bucyrus Erie plant in South Milwaukee (now Caterpillar) mounts huge loads on flats and gons in accordance with AAR and UP rules, but there is additional protection around certain parts that they do not want to get soiled or scratched. A machined end of a shaft for example might have what looks almost like a banded barrel of wood around it to protect the smooth finish of the steel.
I have used Forster Mini-Sticks from a craft store to brace some open loads – see page 3:
http://www.mwr-nmra.org/region/waybill/waybill20112summer.pdf
Dave Nelson
Thank you for posting the link. I would think that all railroads would have close to the same rules. I downloaded the PDF to my computer for later reference.