A protocol is a written plan setting out the question and methods you intend to follow.
A lot of thought may go into writing and submitting a Protocol but it will make things much easier down the track and save you time in the long run.
We recommend registering a systematic review protocol with PROSPERO, but some teams choose to publish their protocols more formally in journals.
The format and content of protocols generally reflects the final paper, so it is worthwhile setting it out well.
Recommended guidelines for Systematic Review Protocols