We present optimized generalized monogamy relations and upper bounds derived from concurrence and concurrence of assistance. We first establish a tighter general upper

 bound of the $\alpha$th ($0\leq\alpha\leq2$) power of concurrence for $N$-qubit states. Then for $N$-qubit systems $ABC_1...C_{N-2}$, the optimized monogamy relations 

and upper bounds satisfied by the $\alpha$th ($0\leq\alpha\leq2$) power of concurrence of $N$-qubit pure states under the partition $AB$ and $C_1...C_{N-2}$, as well as under

 the partition $ABC_1$ and $C_2...C_{N-2}$ are established, which give rise to restrictions on the entanglement distribution and trade offs among the subsystems. Moreover, the 

utilization of the $W$-class states demonstrates that our results are tighter compared with the existing results. Similar results are also obtained for negativity