I can’t do it! I can’t roll my tongue so I can’t do it properly! Is there another way for me to do it well? 
Have you thought of it as trying to make purring noises like a cat?
Hey! “Purr” is onomatopoeic, isn’t it?
Some people make a gargling sound in the back of the throat. It’s less pronounced than a rolled R sound, but it may be a good substitute for you.
Dana
I tought I couldn’t do it till a while ago, when I discovered the back of my tounge. Don’t try to do it with the tip, instead press the back of your tounge up and back a little and purr like a cat like Cathy wrote. You sort of roll your tounge up, can’t describe.
Hope you’ll find it.
Thanks! I’ve tried doing the gargelling thing and can do it with the bottom register, but I can’t get the higher notes out.