I've often suspected that I am on the lower spectrum of autism and a nurse kind of confirmed it. What I want people to know most of all about people like me... is that we're just people 
You don't need to put us in very special episodes, treat us any different and our lives are not governed by our autism. It is also not a reflection on our intelligence. What is true is that we tend to hyper focus on something until it is done, we sometimes have trouble looking at someone in the eye and there is no one size fits all. Autistic people have a different range of quirks, but they are not what you think and chances are, you met an autistic person and didn't know it. And like I said, it's a spectrum and not everyone is on the high side.
Also, when it comes to autistic kids, you have to be patient with them and sensitive. 90% of what they do isn't because they are naughty. They think different and see the world different. However, this doesn't mean they are slow. They're not. Autism means, you think different and your brain is wired different. That's all.
So in short, it's ok for you to subtly hint that a character might be autistic, but please, don't make the source of pity, the stereotype or an invalid. Most importantly, don't make them weird just because they're autistic. My brain may be a little different, but my heart and interests are just like yours.
Most importantly, we have feelings and we are aware of when they're not being considered. Don't portray us in a way you wouldn't want to be just because of your differences.