Even though there's no particular rule that states you have to submit a legal break before filing for separation, there is nothing wrong with doing so, particularly if it's done to continue the union through connection counseling or whatnot. Many couples go their ways from there, and go directly to the divorce, claiming irreconcilable differences.
Be certain to file a motion for temporary orders if filing for a divorce. This is crucial to ensure that the spouse does not go taking sums of cash out of accounts or racking up debt.
This is an excellent solution. If you are currently looking to file for divorce and are in a legal separation, you will want to file and serve the documents with the dissolution of marriage request to her. Though rules differ from one state to another, generally, it is possible to convert the legal separation you filed in a divorce rather simple, but it is never a bad idea to do a little research about what your state and state courts advocate about filing one over another.
See an example of forms for filing for separation.