Normally solder-able spade plugs come with a corresponding rubber boot. The latest Jaycar* packet (P/N: PT4630) didn't have these, so I designed up a protective boot that can be printed out - preferably in something like Ninjaflex:
These printed out really nicely
You can find the STL file and more photos here: http://www.thingiverse.com/thing:1676502
* Bunnings only had crimp connectors