Transmission electron microscopy (TEM) has played a significant role in the characterization of cellulosic materials, especially the so-called “nanocelluloses” (nanofibers and nanocrystals), from visualizing nanoscale morphologies to identifying crystal structures. With scientific and industrial interest in nanocelluloses rapidly increasing, this technique is more important than ever for scientists, engineers and students. Mastering TEM techniques for cellulosic materials is not trivial for a number of reasons, the main one being the high sensitivity of cellulose crystals to electron beam damage. In this contribution, practical aspects of sample preparation, contrast enhancing protocols as well as specific imaging and diffraction techniques are described to facilitate the morphological and structural characterization of cellulose by TEM in imaging and electron diffraction modes. We especially emphasize the importance of controlling the radiation dose to record well-resolved images of cellulose crystals with meaningful structural detail.