You can file any paper you like on your own, finallyseewhy. Here is a resource: How To File For A Legal Separation.
In fact, I would definitely suggest that you learn all you can on court, court proceedings, filing, motions, etc. Knowledge is strength!
However you know the old joke, right? "A man who represents himself has a fool for a client" (~Abe Lincoln)
My advice would be to think of your lawyer the same way you think of your doctor. NO ONE knows you, your situation, and what you need and want better than YOU. Thus you direct them what you want and make sure that's what they do. You ask them for counsel and wisely consider what they suggest, but in the end the decision is YOURS to make, not theirs.
Lawyer does not equal "now I'm not responsible." So learn all that you can, and let your lawyer know that you are interested in doing as much of the paperwork yourself as possible. Maybe you can fill things out and have him review/okay them for errors or suggestions. That saves you lawyer fees but covers your heiney.