I've gotten lucky and been a Veteran quite a lot lately. I do enjoy this role, so it's about time I give you my take on the paranoid war hero. Here's the Veteran.
The role is quite simple: You get three alerts. And every night you use one, you kill any-, and everyone who visits you.
My first and most important piece of advice for all Veterans out there is this: Leave your name in your Death Note. There is no reason not to do this, as the evil roles will already know who you are by the time you've killed one of them and the townies might lynch you if they dont know it's you. So always leave your own name in your Death Note.
My Veteran's Death Note always looks like this:
Saturn the Veteran commands thee to get off his lawn!!
- sincerely, Saturn the Vet
Sometimes I add "I told you so" to it, because I give people a fair warning most, if not all of the time. Why? Because it's just more bluffs and mind games to screw over the enemies' heads... And that is EXACTLY what you want to be doing as the Vet!
Like most of my favourite roles, as the Vet, you want to try and understand the mentality of th people you're playing with. Play with traps, both figuratively and very literally too, to lure the evildoers into their deaths.
Obviously I should point out the obvious fact of obviousness first... obviously: Your alerts are best kept till late-game.
That being said, who likes dying in the first night? I sure dont. So what I do on the first day is try to speak first. Even if you just say hello. Because for whatever reason they might have, most evil roles aim for the talky people first. Sure you could argue that it's in their best interest if the town is silent and passive, but I prefer calling it a dick move.
Something else you could do, that I prefer doing that just saying hello, is saying something along the lines of: "Pro Tipp guys, dont visit me tonight."
In my experience, saying that on the first day got me at least one kill in almost every game as a Vet. Admitted, i did kill half the town and not a single evil role in one particular round, but in my defence, i warned them. And the rest of the town knew I was Vet afterwards because of my Death Note.
You could also use that opening line if you're not a Vet, because many people might be intimidated by a possible Veteran-bluff.
Anyhow, if you managed to kill someone, then people will know you're a Townie. So they should trust you. You might want to remind the town not to visit you ever... Because some people need reminding...
Also, if someone whispers to you saying that he's the Doctor and he wants to "heal you to save your alerts", just be slightly weary. What he says might be perfectly true, but he also may be an evil role trying to keep you from going on alert. Dont trust anyone as a Veteran, unless they reliably prove their own innocence first.
In any case, if you've proven that you're the Vet with your Death Note, then there is no reason to use your alerts in the next few nights. People will know that you're a risk not worth taking. Keep two remaining alerts for later. Occasionally give the evil roles a bluff to think about if you feel like it.
Know that most Vets use all their alerts in the first four nights. Players know this. So if you played by my strategy so far, it should be day four and you should still have two alerts left. Brilliant. Now's the time to lure your attackers in.
You could just lay low and hope people are thinking you're trying to not draw attention to yourself. They'll think you're being quiet because you're all out of alerts. You could also straight out be super obvious and pray that they think you're bluffing.
And if it's really late into the game. For example if it's just you and an evil role left. I suggest being super honest with him. Say that you still have alerts left and you dont mind stretching the game out for a draw. Honesty is always the best kind of deception. Just take my great Amnesiac-Jester game from a little while ago. That was hilarious.
Different round. Assume you havent proven that you're the Vet yet. Nobody knows what role you have. You should pretend to be an investigative role. But the good kind of investigator "who'd rather double check". People will take that bait and attack you before you reveal your information. You might cause some collateral damage by killing some townies too, but if you get the evildoers, that'll be worth it.
One last thing, if you have proven that you're the Vet with your Death Note, you have made yourself a reliable townie. You have influence over the town and you have all the right to use it! Remind people to not randomly vote someone to death. Tell the jailor who to execute if you know who's evil or neutral. Do what you can to support the townies.
There you go. In short: Put your name into your Death Note and bluff your way to victory. I hope you dont mind the pile of dead bodies on your lawn..