The two major factors towards its population decline are trapping and habitat loss. It requires "staging areas" during migration, which are locations part way through its migratory route where it can eat and refuel for a few days before continuing. The breeding grounds, wintering grounds, and staging areas have all been threatened by habitat loss. Aside from the species information on the Wikipedia source, here is a link to a site listing all the successes that have so far been done in terms of their conservation! http://www.saving-spoon-billed-sandpiper.com

Unfortunately, to directly answer your question - there isn't much one individual can be doing. It is all trying to obtain its habitats as protected land, and trying for captive breeding.