1. Start with Tables, Not Ranges

Convert raw data into a Table (Ctrl + T). Tables auto-expand, keep formulas consistent, and make references readable.

• Use clear column headers like Order Date, Client, Region, Net Revenue.
• Avoid merged cells and blank header rows.

2. Standardize Formats Early

Pick a single format for dates, currencies, and percentages.

• Dates: yyyy-mm-dd for consistency across systems.
• Currency: set the locale once to avoid mixed symbols.
• Text: use PROPER, UPPER, or LOWER to align labels.

3. Remove Duplicates Safely

Use the Remove Duplicates tool, but create a safety column first.

• Add a helper column like =A2&"|"&B2&"|"&C2 for a unique key.
• Sort and scan duplicates before deleting anything.

4. Validate Inputs

Data Validation prevents errors before they appear in reports.

• Dropdown lists for Status or Region.
• Numeric limits for Discount or Quantity.
• Custom warnings for out-of-range values.

5. Build a Repeatable Cleanup Sheet

Create a dedicated "Clean" sheet that references raw data.

• Use TRIM to remove hidden spaces.
• Use SUBSTITUTE to remove unwanted characters.
• Use IFERROR to flag issues instead of hiding them.

Final Check

Run a quick audit: totals, row counts, and spot checks. Professional reporting starts with data you can defend.