The first thing is to sit down with your team and understand all of the information you want to track and how that data should look. Is the field a drop down? If it is a drop down, is it a multi-select drop down or just single select? Do you want to limit the values of the field to just the drop-downs or allow users to free-form type something? This is one area where we strongly recommend that you outsource to an experienced consultant. While you can learn how to do the actual customization by watching a YouTube video or reading the manual, having an expert will get you a much better solution.