Use high-proof neutral spirit like vodka rather than a low-proof one, since alcohol below about 40 percent doesn't extract bitter compounds and oils from roots, barks, and peels efficiently, leaving the final bitters weak and unbalanced. Keep bittering agents like gentian root or wormwood to a small fraction of the total botanical mix, since these ingredients are extremely potent and even a small excess makes the whole batch unpleasantly harsh instead of complex. Add different ingredients in stages rather than all at once, since delicate aromatics like citrus peel extract flavor within days while tough roots and barks need several weeks, and steeping everything together for the same length of time under- or over-extracts different components. Shake or agitate the jar every day or two during infusion, since letting it sit completely undisturbed slows extraction and leads to an inconsistent final flavor. Strain the mixture through a fine cloth or coffee filter rather than a basic mesh strainer, since small particles left in the bitters continue to extract flavor unevenly over time and can make the final product cloudy or gritty. Store finished bitters in a small dropper bottle, since bitters are meant to be used in small dashes, and a large jar with no easy way to measure a few drops makes it easy to overpour and throw off a drink's balance.
