If you are already using encryption, you should already be using plausible deniability. I use Veracrypt, and I use its hidden volume feature, which gives a decoy and real password. The decoy volume's password can be safely revealed to anyone demanding the password, assuming you haven't stored any incriminating files in it. The hidden volume's password is the real password, which you would keep as a secret to only yourself where you will store any files which contain sensititive information you wouldn't want other people to know about.
Yes, I've used similar in Truecrypt in past. IDK how this could be implemented in regular user's inbox / outbox without confusing legit receiver or sender.
There's a big problem with this approach, although an increased use of chaff seems inevitable. That is that, by and large, you don't want to have to be in the position of plausible deniability in the first place:- you want to stay under the radar of all the laughably described "targeted" selectors which have huge false positive rates. Sadly, the mere fact that you care about your privacy, use encryption, VPN, Tor etc. appears to be prima facie grounds for suspicion, which is a disgraceful state of affairs, but bought about because of the mass surveillance power-grab and the empire-building enthusiasm for data mining snake-oil sales pitches with inadequate oversight and protection of rights. Mirimir's approach of using VPN first is consistent with not wanting to stand out too much, and in a way, the use of multiple personas is a form of plausible deniability. If you have a public persona, then you can deny that any of the other ones have anything to do with you, as long as your opsec is good (not an easy task).
Those points are solid. Several of us use fairly solid methods. The real problem for me is communicating outside of my "hobby friends" channel. I can easily communicate securely with Mirmir (since his name was already mentioned above) because we share a passion for how to do it. e.g. hidden servers, pgp, etc..... Unfortunately my "real name" friends just don't even care. So I reduce to several internet persona's where privacy becomes everything in that world.
Well, I don't talk about this stuff in meatspace. People probably think that I'm into torrenting and stuff. That's fine by me I only proselytize online. Only way I fly.
This is the essence of the chicken-and-egg problem we have at the moment:- it's hard to construct something even vaguely sound, and the very act of doing so, and the restricted numbers of correspondents who are so inclined, automatically puts you in the oddball-to-be-investigated category. Of course, the VPN-first starter is a way to obfuscate, but it's only a start.
This has been my precise concern for a long time now , and sometimes constrains me from what I'd like to write , and what I am prepared to experiment with for myself . As a recent example , I waited till I was traveling before downloading the latest version of Qubes , then got angry with myself for being " over-cautious " ..... One of my favorite quotes :- " I'm only Bob Dylan when I leave the house "