MD2 models should be about 44 GL units tall and centered on the origin.
MD2 skins are a bit tricky to load. In general the MD2 filter attempts to load skins in the following manner:
When saving models as MD2 it is important to note that MD2 models only use one texture as a skin at any given time. All vertices of the model must be mapped to the same texture. You may include different colorings of the same texture for different skins and add those to the model as additional textures. Those textures should be available as alternate skins for the model.
MD2 animations specify vertex positions for each vertex for each frame of each animation. This can be tedious. When creating a model from scratch it is usually easier to save the model in MM3D format and create skeletal animations. Then when you are ready to export to MD2, convert the skeletal animations to frame animations using the Animation Sets Window and save as an MD2.
Because of the enormous overhead of saving undo information for animations upon insertion and deletion of vertex and face primitives, you are not allowed to add or remove primitives from a model that has frame animations. You may, however, merge another existing model into the one you are working on. This is another reason why it is best to work with MM3D files and skeletal animations and only export MD2 files when necessary.
MD2 files save triangle strip information for optimized model drawing. Maverick Model 3D is rather dumb about triangle strips by default and creates a triangle fan for each triangle. If you want smarter triangle strips see the ACTC triangle stripping plugin on the Misfit Model 3D plugins webpage.
Note that plugins are only available on Linux and Mac OS X systems. Plugin support is not available on Windows systems at this time.