Whole Site Changes
Ideally, some or all of the following changes are made to improve the overall security of the path to the Landing Page and obfuscate traffic analysis.
Make your entire site available through HTTPS.
That way, visits to your Landing Page won’t stand out as the only encrypted traffic to your site.
Include an iframe for all (or a random subset of) visitors, loading this particular URL (hidden).
By artificially generating traffic to the endpoint it will be harder to distinguish these from other, ‘real’ requests.
Use a random delay for adding the iframe (otherwise the ‘pairing’ with the initial HTTP request may distinguish this traffic).
Print the link, URL and info block on the dead trees (the paper), as others have suggested.
Add HSTS headers.
For publicly advertised SecureDrop instances display the Source Interface’s Onion Service onion address on all of the organization public pages.
Mirror Tor Browser and Tails so sources do not have to visit torproject.org to download it.