modifying for the individual not the disability

Yes, it's helpful to know about autism if you have an individual with autism in your ministry. (And I would add, given the increase in prevalence of autism spectrum disorders in recent history, you should probably go ahead and educate yourself about those disorders even if you don't have anyone with autism at your church yet.)

However, every person is different. Every individual is uniquely created by our creative God. You wouldn't expect every 35-year-old woman at your church to act in the same way, or every 5-year-old girl, or every teenager. Likewise, it doesn't make sense to expect every child with special needs to act the same or every child with Down syndrome to need the same support on Sunday morning.

Special needs ministry isn't about the disability. It's about the person and the family.

If you want to minister to and with people with special needs, I don't suggest that you study disabilities first.
Study people instead.

Become a student of your families. Ask questions about strengths and weaknesses, about what the person does and doesn't respond well to. Don't make assumptions based on what you know about the disability; learn all you can about the person. It is helpful to develop an intake form to record specific information; here's a post from The Inclusive church blog about what you might want to include on that form.

And never forget that you can learn as much from the individual with special needs as you can from anyone else. If you're talking to the whole family, do not talk to the parents as if the child does not exist or as if he/she is not present. Don't just learn about the people with special needs in your church; learn from them.

There are no shortcuts, no "if this disability is X, then do Y" formulas. It's not as easy as that.

But, honestly, there aren't any formulas in ministry. All of the books and methods and strategies out there recommending formulaic ministry are missing one truth: Jesus didn't use formulas. He loved people.

And He still does.