I'm still a bit confused.

I had a nice chat with an acquaintance that I ran into in line to register for a course at the college. I was halfway to my car when I remembered, "Rats, I was supposed to pursue acquaintances". I considered going back, but figured that would look too weird and besides, what would I say?

Later that day a woman I know quite well came to my yoga class. After class I reminded her that we had previously tried to go hiking, but it had never happened. I didn't push it but told her I was flexible if she was ever into it. But I doubt anything will come of this.

Today we partnered up in class and the woman I worked with seemed neat and friendly. I showed a lot of interest in her and found out she's new in town and likes to go hiking. But (can you believe it?!) she already has a group of friends she regularly hikes with. And here's where I blew it, big time. She said I should come along and I quickly changed the subject. I'm just not one to impulsively agree to something I just heard of, especially with a group of women I've never met. Of course I'm kicking myself now! The sad part is she won't likely be in the same class as me again, because she told me she has to switch to another day.

So, any other advice on how to change acquaintances into friends? I still have very little idea on what to do.

Stop being scared.

Well, obviously you need to be a bit less instantly remote, and proactively seek connections. You should have said something like "Interesting idea. Can I have your phone number and I can call you to figure something out." Make the reflex action that of a middle of the road ambiguity, rather than a definitive anything.

Instead of changing the subject, ask the aquaintance for details on their hiking event and tell her you'll think about it. You might also ask her a few questions you may have about it, if you have any of course. I know it's hard to not be shy sometimes but if you want friends you have to start/lead the conversation sometimes. You can always expect others to lead/come to you first all the time. Another thing to do is study the individual to see if they would be the type of person you wish to be associated with. Good Luck! A!

"I had a nice chat with an acquaintance that I ran into in line to register for a course at the college. I was halfway to my car when I remembered, "Rats, I was supposed to pursue acquaintances". I considered going back, but figured that would look too weird and besides, what would I say?"

Well played. Once you didn't act on the line, you guessed right that it might seem a bit offbeat to push your luck........

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"Later that day a woman I know quite well came to my yoga class. After class I reminded her that we had previously tried to go hiking, but it had never happened. I didn't push it but told her I was flexible if she was ever into it. But I doubt anything will come of this."

Ok, a miss here on "I reminded her that we had previously tried to go hiking, but it had never happened."

The NT "game" is - you don't remind anybody of any 'promise.'
You COULD say, "Good to see you again. I think you may have mentioned that you hike sometimes? [even though you remember every tiny detail, this is the correct social play here.] I've judt started going to [local area that she's most likely to either have tried already or might want to try; bonus pts if you've ever actually hiked it]."

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"Today we partnered up in class and the woman I worked with seemed neat and friendly. I showed a lot of interest in her and found out she's new in town and likes to go hiking. But (can you believe it?!) she already has a group of friends she regularly hikes with. And here's where I blew it, big time. She said I should come along and I quickly changed the subject. I'm just not one to impulsively agree to something I just heard of, especially with a group of women I've never met. Of course I'm kicking myself now! The sad part is she won't likely be in the same class as me again, because she told me she has to switch to another day."

Your "quickly changed the subject" accident might work for you; sounds like otherwise, you risked seeming TOO eager.
You may run into this woman by chance again there anyway, and if so, any interest you show would likely NOT seem too forward since you didn't leap at the chance the first time; you seemed to have plenty of other options, which is considered appealing.

For what it's worth here is how I think I would have responded to first one, not reminded her but not ignored it either. I would have most likely said "I am so sorry we never got to go on that hike, life just gets so crazy. Maybe we can try it again sometime" puts it out there without being needy. On the second one it sounds like you were just taken by surprise so I like Barts direction but would have said something like "That sounds fun. When do you guys go? Lets exchange numbers and I can let you know before your next hike if I can make it."

My first instinct is the same as yours. This opportunity will probably come back around again though, eventually. Put yourself through every possible scenario mentally so you're less likely to be caught off guard next time. You might also want to think about how you should react if you were to cross paths with her group while hiking.

I don't know about others, but I find that it is MORE difficult to react in a socially appropriate way when I'm with someone else who is not an aspie. I am not just trying to juggle what to say and do with the person I'm meeting (unexpectedly) but also what I'm going to hear about afterwards, possibly for days. I much prefer to be alone in difficult situations like that, as the person with me is not support (unless AS) but another stress factor.

This one paragraph is a goldmine of information when it comes to conversing with NTs and understanding some of their behavior. There is sooo much empty blather that NTs engage in and a lot of it must be there to continually reinforce social bonds/social positioning, or else why would they constantly engage in this seemingly pointless behavior? I have recently taken the initiative when it comes to keeping my "lecturing" down to a minimum and I like the 3 sentence rule a lot, but the other stuff is still completely beyond my comprehension. Most people don't give a crap what is coming out of your mouth about a given subject, and the more you talk, the less they care. It's just mainly used as social lubrication like you said. It took me years and years to figure that out, but I think I'm finally there.

Thanks for all the feedback.

I certainly was caught off guard! I was looking for one hiking companion, not a group to join! The truth is that I don't like groups, especially where they all know each other and I don't; I find that very uncomfortable. Also, my immediate reaction to something unanticipated tends to be negative. I just can't do anything impulsively; I need to think it over first.

But now I'm prepared. If this, or even something similar, should come up again, I'll give it a try.