How should I message a girl over Facebook?

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As a little bit of backstory I went through a really bad breakup a few months back, and am now single for the first time in over seven years.

During that time I've started working a job at home, so I don't get out of the house much to meet new people.

I'm 21 years old, and I came across a girl on Facebook that I used to have a crush on when I was a kid.
I can tell just from observing her profile that we have at least a few things in common, and I think we could get along very well.
But I know I'm never just going to run into her randomly in public or anything like that, and I doubt she'll be single forever.
So while the door is open I want to send her a message and ask her on a date.
But I feel like doing that might be a little weird, because I've lost a lot of my social skills and confidence, so I'm second guessing every possibility I can come up with.

My original thought was just to message a hello, ask them how they've been, and then see if they might want to go to a movie or dinner or something like that. But I feel like it might be a little weird to just come out of the blue and ask her on a date, especially over Facebook.

The other option I was considering was saying hello like before, but this time saying that I was interested in getting to know her a little bit, and hopefully going from there, but again, not sure if that's a great idea.

My last option is a little bit more convoluted. But I used to be really good friends with one of her best friends back in the day, and I also think it's possible for me to reconnect with them, and then ask them for help with the situation.

I could really use any advice on what I should do. I'm not afraid of rejection because I know full well it's always a possibility, but I know if I don't try nothing can come of this at all.
So any advice on what I should do, and how would be greatly appreciated.
Thank you in advance