  Let $V$ be a complex nonsingular projective 3-fold of general type. We prove
$P_{12}(V):=\text{dim} H^0(V, 12K_V)>0$ and $P_{m_0}(V)>1$ for some positive
integer $m_0\leq 24$. A direct consequence is the birationality of the
pluricanonical map $\varphi_m$ for all $m\geq 126$. Besides, the canonical
volume $\text{Vol}(V)$ has a universal lower bound $\nu(3)\geq \frac{1}{63\cdot
126^2}$.
