We propose a novel approach to contact Hamiltonian mechanics which, in contrast to the one dominating in the literature, serves also for non-trivial contact structures. In this approach Hamiltonians are no longer functions on the contact manifold M itself but sections of a line bundle over M or, equivalently, 1-homogeneous functions on a certain GL(1, ℝ)-principal bundle τ : P → M, which is equipped with a homogeneous symplectic form ω. In other words, our understanding of contact geometry is that it is not an ‘odd-dimensional cousin’ of symplectic geometry but rather a part of the latter, namely ‘homogeneous symplec-Jtic geometry’. This understanding of contact structures is much simpler than the traditionalone and very effective in applications, reducing the contact Hamiltonian formalism to thestandard symplectic picture. We develop in this language contact Hamiltonian mechanics inautonomous, as well as time-dependent case, and the corresponding Hamilton-Jacobi theory.Fundamental examples are based on canonical contact structures on the first jet bundles1(L) of sections of line bundles L, which play in contact geometry a fundamental rˆole, similar to that played by cotangent bundles in symplectic geometry.