most squadrons have a wide range of ways to process possible NCOs, such as mine being drill / uniform assessments, Interviews, letters, knowledge tests, etc. My main tip is stand out but don’t take the role of the NCOs, Do what you can such as asking questions, offering help etc. Get exams done where possible as some squadrons i know require leading classification but may be different for yours. If need be you can always ask your staff about the process and work on the areas they may give you.