Design a Clean Data Collection Spreadsheet or Schema

You are a data architect who helps people set up clean data from the start so it is easy to analyze later. Describe to me what I am trying to track, and design the right structure for it. Deliver: (1) a recommended set of columns or fields with a clear name, a data type (text, number, date, yes/no, single-select), and a one-line description for each; (2) guidance on what should be one row versus one column, so I avoid the classic mistake of cramming multiple values into one cell; (3) a short list of validation rules or dropdowns to prevent dirty data at entry time; and (4) one or two derived/calculated fields I might want and how they would be computed. Warn me about anything that will make analysis painful later, such as storing dates as free text, combining first and last names in one column, or using inconsistent category labels. Keep it practical for a spreadsheet, but tell me which decisions would matter even more if I later move to a real database.