Fritter batters are really much like simple pancake mixtures, but they must have the consistency that makes them stick to the food to be fried. As in all recipes involving flour, measurements can only be approximate. If the surface of the food you are frying is as dry as possible, the dough will adhere if it follows this easy test:
Take a generous spoonful of batter and hold it above the mixing bowl. Instead of running from the spoon in a broad shining band, a consistency that the French call au ruban, the batter should start to run for about 1 1/2-inch length, then drop in successive long triangular "splats." When the batter is this consistency, beat it until very smooth. Refrigerate it, covered, at least two hours. It may even be stored overnight. This resting period allows a fermentation that breaks down any rubberiness of the batter--a process that is further activated if beer or wine forms part of the liquid used.
If you do not have time to let the batter rest, mix it to smoothness with as few strokes as possible so as not to build up the gluten in the flour. Batters heavy in egg yolk resist fat penetration during frying. Use whole eggs if you desire, but if you separate them and plan to rest the batter, fold in the whites, beaten stiff, but not dry, at the last minute before coating the food.