Learn to know a plant even in winter. Start by clipping a couple of twigs from shrubs or trees you know, then sit down with a plant encyclopedia to compare the real things to their description.
There are specific technical terms to describe every aspect of a bud or leafless twig, from the density of fuzziness on the twig ("scabrous" has short stiff hairs, while "tomentose" is wooly) to the arrangement of buds (opposite each other, alternating sides on the twig, whorled, etc.) to the number and shape of spots where last year's leaf veins left "bundle scars" within the bud scar. University of California, Berkley's Herbarium and other schools post such dictionaries.
Fortunately, gardeners only have to look for and find some characteristic of each plant that speaks to them, to remember it always. For instance, we recognize poplar for its very large, sticky, tip buds and tree of heaven (twig and bud shown below) for the yeasty smell of a broken twig.
Not all plant encyclopedias include twig- and bud descriptions, drawings or photos. When we're trying to put a name to a leafless plant, we use:
We also use the USDA's plant data base for line drawings of twigs, or use an Internet Search engine clicked to "Images" so we can compare our twigs to the results to find a match.
Growth habits can be telltale of a species, too. We recognize the bark of an oak but can also look up, and up the trunk to see that it is holding foliage through winter, confirming the identification. Seeing the leaves with their pointed lobes we can also be pretty sure it's a species in the red oak group, probably northern red oak (Quercus rubra).