Since my daughter's diagnosis, she has been much happier and allowed to be more herself instead of shoved into acting more "normal" which is what everyone was trying to do.
I find it extraordinarily sad that a kid needs a diagnosis in order to be "allowed" to be themselves to begin with. The fact that people, by default, want to shove everyone into the same stupid box speaks volumes about our society, and not in a good way.
I've found a lot of parenting articles I've read on ASD children are written more to neurotypical parents. You're supposed to keep calm, give choices, go through some sensory routines, etc. Ok, that's great and all, but what do you do if your own nervous system is going bonkers at the same time? I try, but it's sooo difficult and I feel like a failure.
The advice is still sound for AS/D parents, and I've found that forcing my voice to stay calm also helps me cope with the situation when it does escalate to that point. If all else fails, I tag-team with my husband, because in the moment, it's generally a "good cop, bad cop" type of thing and the first responding parent is the "bad cop" to my son. By letting one of us be the "bad guy" for the escalation part, it makes my son be more receptive to the other parent.
That said, I've found the best way to deal with those situations is to preempt them. I've found there are a number of ways to do this.
My son and I have probably about a 75% overlap in what sensory input overstimulates us, so I've learned to trust my own senses, and if I feel like I'm getting overwhelmed by the environment, I bring up those concerns and I try to be mindful about what, exactly, is causing that, so I can find ways to either adapt the environment or give my son adaptations. In situations where I can't control the environment and his physical coping tools aren't adequate, I can go in prepared to have to deal with a meltdown, either by planning a way to break away for a while so he can get a break, or making sure we're not in that environment for too long.
I've also learned to watch for his pre-meltdown, "I'm getting overstimulated" cues. Since his big sensory overload sense is hearing, he'll often start folding his ear into his ear canal, basically in an attempt to block out the sound. That's the cue to get him to a quiet place, or at the least, get him headphones to block out the sound. By catching the signs of a meltdown before it happens, it saves both him and me from the nervous system explosion that often happens in that situation.
We've also taught him that his bedroom is his safe place, where he can go when he needs some time to chill, and we'll respect that. It's painted a very dark blue, and has a curtain on the one window, so it stays pretty dark even in the day time. Sometimes, we'll have him go to his room when he already starts into the meltdown, but we've done our best to make sure he realizes that it's not punishment, because I refuse to punish him for melting down (if he gets to the point that he's destroying things, that's a bit different, but it's largely a matter of "these are the consequences of your actions here, so let's try to avoid getting to this point"). Likewise, we've worked with his school and the after school program to ensure he has a quiet place to retreat to for a little bit. At school, it's the intervention specialist's room and at the after school program, it's just a spare room that's generally unoccupied. It's been working phenomenally well, and when he starts getting overwhelmed, he simply goes to that room for about 20 minutes, and then he's ready to rejoin the main group.
Personally, I need to watch it with my Aspie son. He is constantly disobedient and I try to enforce discipline with stern voice, posture, etc., but I am getting the impression that he is afraid of me, as he generally prefers his mom over me. She is easier on him though. I get attacked for not being affectionate enough, but how do you get affectionate with an aloof kid? I do not have these issues with my daughter at all. She takes readily to me. She does have her issues though. Tell her what she cannot have or do and you'll have a fit throwing drama queen thrashing around on the floor!
How do you be affectionate with an aloof kid? Realize that affection doesn't have to mean hugs and kisses. Affection can be sharing in what he likes to do, or just listening to him talk about his special interest.
For example, my son is big into Pokemon right now. He can name a good chunk of at least the original couple of sets and is greatly enjoying the card game. So, we play a round or two with him each night (which is easier now that we have a couple of decks for a little variety), and he absolutely loves it.
If you're doing stuff like that, the haters can go pound sand.
As for the discipline, I think the stuff above this quote will be helpful for you, too.