Cash Back Stacking: combining Portals, Cards, and Receipts

# Role
Expert Personal Finance Advisor specializing in maximizing cashback rewards.

# Context
Consumers are constantly seeking ways to save money on their purchases. Cashback programs offered by portals like Rakuten, rewards credit cards, and receipt scanning apps such as Fetch provide an opportunity to "stack" savings and significantly increase overall cashback earnings on a single purchase. A comprehensive guide explaining this strategy is needed.

# Task
Create a shopping optimization guide that clearly explains the "Cash Back Stacking" method. The guide should:

1.  **Introduction:** Briefly explain what "Cash Back Stacking" is and its benefits.
2.  **Cashback Portals (e.g., Rakuten):**
    *   Explain how cashback portals work.
    *   Provide a step-by-step guide on how to use a cashback portal (e.g., Rakuten) for online purchases. Include screenshots or examples (hypothetical values are acceptable).
    *   Explain the importance of checking portal rates before making a purchase and potential rate fluctuations.
3.  **Rewards Credit Cards:**
    *   Explain how rewards credit cards work and the different types of rewards (cashback, points, miles).
    *   Emphasize the importance of using a rewards credit card that aligns with the spending category (e.g., a card with bonus points for online purchases).
    *   Explain how to use a rewards credit card in conjunction with a cashback portal.
4.  **Receipt Scanning Apps (e.g., Fetch):**
    *   Explain how receipt scanning apps work and how they provide additional cashback.
    *   Provide a step-by-step guide on how to scan receipts using a receipt scanning app (e.g., Fetch). Include screenshots or examples (hypothetical values are acceptable).
    *   Explain the types of rewards offered by receipt scanning apps (e.g., points redeemable for gift cards).
5.  **Stacking Example:**
    *   Provide a detailed example illustrating how to stack cashback portal rewards, credit card rewards, and receipt scanning app rewards on a single purchase. Include hypothetical values for each step.
    *   Clearly show the total savings achieved through stacking versus not stacking.
6.  **Tips & Tricks:**
    *   Offer tips for maximizing cashback rewards, such as:
        *   Using browser extensions to automatically activate cashback.
        *   Checking for promo codes and coupons to combine with cashback.
        *   Referring friends to cashback programs and apps.
        *   Understanding the terms and conditions of each program.
7.  **Potential Pitfalls:**
    *   Highlight potential pitfalls to avoid, such as:
        *   Forgetting to activate the cashback portal before making a purchase.
        *   Returning items that could void cashback.
        *   Spending more money than intended just to earn cashback.
8.  **Conclusion:** Summarize the benefits of Cash Back Stacking and encourage readers to implement the strategy.

# Constraints
1.  The guide should be written in a clear, concise, and easy-to-understand language. Avoid jargon.
2.  Maintain a positive and encouraging tone, emphasizing the benefits of saving money.
3.  Include hypothetical examples and values to illustrate the concepts effectively.
4.  The guide should be practical and actionable, providing readers with clear steps to implement the strategy.
5.  Focus on general principles and avoid recommending specific credit cards or cashback apps unless for example purposes (Rakuten and Fetch are specified).

# Output Format
Markdown Document:

*   Headings and subheadings should be used to structure the content.
*   Numbered lists should be used for step-by-step instructions.
*   Bullet points should be used for listing tips and tricks.
*   Hypothetical examples should be clearly labeled as such.
*   Include a table summarizing the "Stacking Example" showing the different rewards sources.