Creating a reliable stream of passive income from ASX shares may seem like an intimidating task, but it doesn't have to be.

With the right strategy and a disciplined approach, 2025 could be the year you set the foundation for a robust passive income portfolio. Here are three steps to help you get started.

Step 1: Focus on high-quality dividend stocks

The cornerstone of any passive income portfolio is high-quality ASX dividend stocks. These are companies with strong balance sheets, consistent earnings, and a track record of paying (and increasing) dividends over time.

Think ASX-listed giants like Telstra Group Ltd (ASX: TLS) and Coles Group Ltd (ASX: COL), which have demonstrated resilience across economic cycles.

Investors may also want to look for businesses with manageable payout ratios and sustainable growth potential. A payout ratio below 75% is typically a good sign, as it leaves room for the company to reinvest in growth while also rewarding shareholders.

Step 2: Reinvest your dividends

While it can be tempting to cash out your dividends as soon as they are paid, it may not be the smartest move.

Reinvesting your dividends can significantly accelerate the growth of your passive income machine. By opting into dividend reinvestment plans (DRPs), you can automatically use your payouts to buy more shares. This process harnesses the power of compounding, where reinvested earnings generate their own returns over time.

For example, reinvesting a 5% dividend yield on a $50,000 portfolio could grow your holdings substantially over a decade, especially if the underlying shares also appreciate in value.

Step 3: Diversify for stability

It can be tempting to chase the highest dividend yields, but diversification is crucial to mitigate risks. Relying too heavily on one sector, such as the banks or miners, can expose your portfolio to economic shocks.

Instead, passive income investors may want to aim to spread their investments across multiple other industries such as healthcare, utilities, and real estate.

Including ETFs like the Vanguard Australian Shares High Yield ETF (ASX: VHY) can also help with diversification. This fund allows investors to buy a diverse group of the largest dividend payers on the Australian share market with a single click of the button.

Foolish takeaway

Building a passive income machine from ASX shares requires patience, discipline, and a long-term mindset.

But by investing in quality dividend stocks, reinvesting your earnings, and maintaining a diversified portfolio, you could create a stream of income that grows year after year.

By starting today, by the time 2025 draws to a close, you could be on your way to enjoying financial independence through the power of passive income.