回复：请教NIW，自己办好，还是找律师？律师的作用是什么，有多大？多谢。

Really up to yourself: how much you know NIW? and whether you can spend a great deal of time and efforts to prepare your materials? how strong of your background?

Attorney can help you, but you do most of work. If you want to hire attorney, I strongly suggest to be sure to get good one! In many cases, it is poor lawyer to bring your bad luck and pain - my lesson!