When you only need a little, don't bother with a scale. Dry ingredients in small amounts can be measured accurately by volume, using measuring spoons. Superaccurate measurement of dry ingredients is only important in recipes in which the dry ingredient plays a critical role. This includes almost all bread and pastry recipes. Flours, starches, cocoa powder, and confectioners' sugar are all best measured by weight.
Granulated sugar is an exception.
Nuts should be measured by weight when they are a major part of the structure of the recipe. For example, the ground nuts in a dacquoise meringue or in a nut cake should be weighed, but the nuts used just as a flavor accent in brownies or cookies can be measured in a cup. The chemistry of the recipe won't really be affected by a few more or less nuts, just the flavor and texture. Small amounts are fine measured by volume. No matter which method you choose, be sure to use good equipment and to follow the recipe directions accurately.