For proper extraction, grinding properly is essential. Freshly grinding coffee before brewing is on of the most important steps for achieving a quality cup of coffee. Coffee should not be ground more that 2 minutes before brewing or major staling (oxidation) begins to take place.
There are two main types of grinders available. Blade grinders sell for about $20, grind the bean unevenly, and are messy. Burr grinders are about $60-$125, grind evenly, and are clean and easy. The extra money for the burr grinder is one of the best investments one can make for improving cup quality and ones sanity.
For any specific analysis, a blade grinder is unacceptable due to it’s lack of reproducibility.
Burrs should be replaced periodically (every 600-2000 lbs. of coffee), but for typical home use it is only necessary to clean the burrs.
Each brewing method required a different grind size: Drip coffee requires a medium size grind, espresso requires a fine size grind, a French press requires the largest grind size, while the vacuum pot also requires the largest grind. For cupping, it is preferred to use a French size press.