You need a codeword - short phrase - unlikely for others to say unknowingly - can be snuck into a post
Tell all of your prisoners this codeword. Sneak the codeword into a post if you are at risk of being lynched. Former prisoners will switch their votes and come to your defense. You won't have to expose your identity until this moment and the public still won't know there's a Jailor.
Defining some terms: early-game - Day 1-3 mid-game - Day 4-6 late-game - Day 7-
Keeping Town in the dark is usually a good policy for any role. Power role information disproportionately benefits Mafia in the early-game. A mid-game reveal should help narrow down the suspect list. Your role will wreck Mafia if you survive to late-game.
Reveal if a former prisoner's public roleclaim contradicts their jailed roleclaim. Lying rarely benefits Town, so liars are either scum or dumb.
Jail targets: Early - Anyone Mid - Exposed power roles Late - Mafia suspects
Future prisoners: - force them to give you their role - explain the codeword - instruct them to keep quiet about jailor
Don't tell prisoners about each other (identities, roles)