Best luck, Molly Rose!
I was slightly older when I started hitching around the country, and wasn't prepared for the level of concern-trolling I ran into, so I'd tell you what I didn't realize at first - ie, if you ask people if you think X spot is a good place to find a ride east/west X far, and they go, "no no this is a really bad spot," - it's not that you're actually in a bad place, they'd just say that about anywhere.
Most were people who'd never lived on the road themselves, and the people who were former travelers themselves generally were a lot more understanding / easier to strike up a rapport with.
But a few times, I had people who seemed worried for me because they themselves ran into trouble back when they were doing what I was doing.
Once recently a man told me that he'd thumbed his way through different countries years ago, and had done mostly okay, but had a few jarring experiences with people threatening and propositioning him once he was in their cars. And it was shocking and he wouldn't want me to run into anything like that!
I understood his good intent, but only a man could be so shocked! Only a man could be so unprepared, because he has no experience confronting that kind of violence in the supermarket, the bar, the downtown street at night, the downtown street in broad daylight, the workplace, the home, the Greyhound bus. But the rest of us?
We know a bit better.
(I did have to physically fight a guy the last time I was riding a greyhound, fwiw.)
With people like that, they're basically sympathetic and benign.
Other times you get people who are real determined to prove something to you, who fixate on telling you that you can't actually be okay in your situation, no matter what you say. Although I've never run into the kind of acute danger some other travelers have, there *is* a real cumulative harm that comes from dozens of people ranting at you about your imminent murder. These good concerned people who want to warn me about the Bad People have been my biggest source of aggrivation and burnout on the road.
So I don't like to get into contrived or scripted communication, but I've found it's kind of important to practice standard responses to have ready for deflecting and shutting down BS from people on power trips about that stuff, ie,
What makes you think that's an appropriate question to ask a stranger?
You don't need to worry about that.
You don't need to concern yourself with that.
(re: are you running into violence/harassment from other drivers?)
Dirty talk is five dollars a minute.
(cautionary note: sometimes people actually give you money. spend the minutes describing encounters with evangelical christians in excruciating detail.)
(re: are you armed?)
As long as you keep being respectful, that won't be an issue.
I haven't had to hurt anyone yet.
(re: be careful)
You too.
No thank you.