#1
If it is really secret then don't write it down, forget it and never talk about it, not even your colleagues and heavens forbid your superiors.
#2
If it is really secret but also really important that it should be preserved and you are absolutely 'put your life on the line' sure about it then make sure you spread enough 'information'. Preferably related to it but meaning the opposite and meaning the same but unrelated to it, the quantity of misinformation counts the most.
Do so in at least in the main stream languages from every major region.
Involve colleagues and superiors to help you but never mention what is the actual accurate intelligence unless it is the person who is on a need to know basis.
#3
There is no correlation between hard to get information and its accuracy
#4
There is no correlation between hard to get information and easiness to protect it.
Strive for not common known available, create an action plan for when using this information the worsted case scenario happens.
#5
Never assume because it is 'near' impossible to decode information that it is impossible to do so, the future is sooner then later.
#6
You are not special, if you can figure it out then at least one person who is at the moment considered your enemy can find it out too.
If 'it' came from the enemy then treat the content as if it was made available on purpose by the enemy unless proven otherwise.
#7
The walls have ears
#8
So have the ceilings, your car, your phone, the bypassing colleague, the open air and everything else which is not in the silent room, which is inspected by your self for electro-magnetic and sound leakages prior your intend to communicate.
#9
When confronted with an opponent that is prepared to die for their cause, don't let them down but keep well out of their way. History is not written by the dead but by the ones that lived.
#10
Eventually people will defend if they have something to loose.
Eventually people will attack when they having nothing more to loose. Give them just enough to prevent them from defending or more than what your opponents give you, whatever is the least.
So what does this all mean?
The information you get is probably not that interesting or important.