Key metricsDividend yield and other key metricsBefore you buy any dividend stocks, it's important to know how to evaluate them. These metrics can help you understand how much in dividends to expect, how reliable a dividend might be, and -- most importantly -- how to identify red flags.Dividend yieldThe is the annualized dividend represented as a percentage of the stock price. For instance, if a company pays $1 in annualized dividends and the stock costs $20 per share, the dividend yield would be 5%.Yield is useful as a valuation metric when you compare a stock's current yield to its historical levels. A higher dividend yield is better, all other things being equal, but a company's ability to maintain the dividend payout -- and, ideally, increase it -- matters even more. An abnormally high dividend yield could be a red flag.Dividend payout ratioThis is the dividend as a percentage of a company's earnings. If a company earns $1 per share in net income and pays a $0.50-per-share dividend, the is 50%. In general terms, the lower the payout ratio, the more sustainable a dividend is.Cash dividend payout ratioThis is the dividend as a percentage of a company's operating cash flows minus capital expenditures, or . This metric is relevant because net income is not a cash measure.Various noncash expenses can cause a company's earnings and FCF to vary significantly from one period to the next. This variability can cause a company's payout ratio to be misleading at times. Investors can use the cash dividend payout ratio, along with the simple payout ratio, to better understand a dividend's sustainability., Plus, we highlight how you can find stocks that make regular payments to shareholders, and explore the two popular dividend investing strategies. Keep reading to learn how to buy dividend stocks as an investor in the UK., Dividend investing is a profitable and proven method to generate solid long-term returns. But investors must be tactical when choosing the best dividend stocks..