P.G.
Visit autismspeaks.org - they have toolkits and one of them may be safety related. You can also contact them and they may have ways to help.
You need to remember that YOU ARE NOT FAILING. Autism is a neurological wiring issue. His brain just works differently - trying to figure out how it works and how to work with it to help him function in the world is the big challenge. You're not failing at it, you're trying your best to make it work.
My son is also autistic and I can see that he thinks differently. Very logic based, very literal. Rules work for him, especially when they make sense. I don't know if your guy is rule based, but if you can figure out what works for him re. behavior, try to use that in other areas.
There's a blog that I discovered - adiaryofamom.wordpress.com - it's a mom with a neuro-typical daugher and an autistic daughter, and her experience form diagnosis to the present. You may find some helpful stuff in there in general.