I can imagine homeschooling pre-internet, but then again, it's pretty hard to imagine, too. It sounds like a nebulous, hard-to-navigate place...
One website--homeschoolreviews.com--has been enormously beneficial to me. We all have different needs and tastes when it comes to curriculum, so even asking one or two friends about a particular series, even if you really respect how your friend homeschools, is only helpful up to a point. Listening to one homeschooling guru, even if you find that person incredibly wise (such as Susan Wise Bauer), still only helps to a certain degree. What you need is lots of input so you can get a feel for a given curriculum.
You know how recipe websites allow users to comment? And you glance through the first twenty and begin to see a pattern--too much butter, or better if cooked ten minutes longer, or ehhhh, this was not worth the amount of time it took.
Well, homeschoolreviews.com is like that. If you read sixty reviews of Singapore Math, you start to get a feel for Singapore Math. You read some reviews that strike you as written by crazy people, some that are premature (their kid has been using the curriculum for two weeks), but stumble across quite a few that are helpful. Sometimes people say things like, "This worked great for one of my kids but not the other, and here's why...," or things like, "This is a great series, but know that when you reach fourth grade, the content level suddenly jumps to a much higher level. We found it helpful to supplement with this other curriculum and that did the trick."
And after you read enough reviews like that, you start to see patterns.
So far, every curriculum I've ordered has been what I've expected, thanks to homeschoolreviews.com.
And I've learned which curriculum exist due to homeschoolreviews.com. Also, people bring up factors I hadn't even thought to consider. Helpful.
By all means, talk to your friends and flip through their copies of books before you order them. But this is a pretty great place to start, I think.