Is there any other recommended data I should store in the vertex buffers aside from a vertex' coordinates, normals and texture coordinates? For example data I'd need for a feature that almost every mature game engine implements later on?
If you do tangent space normal mapping, as practically every game does nowdays, you should also store tangent space (binormal and tangent in addition to normal). For skinned characters you also need to store multiple (usually 4) bone indices and weights.
In addition there can be multiple UV coordinates, some texture blending weights, color data, spherical harmonic coefficient, etcetc. as well, but it really depends what kind of graphics features and algorithms you implement.