Although I agree with Fagus being good for bonsai in general, I would not recommend them as a first tree. They are a bit more picky on watering, light and funicky about their roots.
Good that you start with thinking ahead. Even though leav size is only important once you get closer to the final image, for a good bonsai, leaf size is important, and therefor a very relevant selection criterium. Fagus do reduce leaves and they can go down to about 2 cm.
Depending on the area you are in..
Trident maple are pretty indestructable and good starting trees,
as are Larix (The latter you only have to report at the right time; Too late in spring will kill it).