The V60 rewards attention to a few variables: dose, ratio, grind size, and pour technique. Get those roughly right and the rest is refinement.
Ratio
A good starting point is 1:16: for every gram of coffee, sixteen grams of water. For a single cup, try 20 g of coffee and 320 g of water.
Use the coffee-to-water ratio calculator to resize the recipe or calculate the coffee dose from the water available.
Whole grams, from 1 to 200.
More concentrated at 1:10, lighter at 1:20.
Grind
Aim for medium-fine, similar to table salt. If the brew tastes sour and the drawdown is fast, grind finer. If it tastes bitter and drains slowly, grind coarser.
Pouring
Start with a bloom: pour twice the coffee’s weight in water, wait 30-45 seconds, then pour the rest in slow spirals, keeping the water level steady.