: You "buy" a credit line by providing a cash deposit (e.g., $200–$500) as collateral, which helps establish a positive payment history.

: Using disposable income to reduce credit card balances is the fastest way to boost your score by lowering your credit utilization ratio .

The most effective "buy-in" for a better score involves using your capital to leverage legitimate credit-building tools and strategic debt reduction. Legitimate Ways to "Invest" in Your Credit Score

How to Improve Your Credit Score in 7 Steps - Charles Schwab