How Do You Research a Stock Before Buying It for the Long Term?

When choosing a stock for a long-term investment, looking only at the current share price doesn't tell you much about whether the company is actually attractive. What do you normally check first—revenue growth, earnings, debt, free cash flow, valuation, competition, or the company's future growth potential? I'm curious how other investors approach their research before buying a stock and which financial metrics they consider the most important.