A sequential SAT solver Satori was recently proposed as an alternative to combinational SAT in verification applications. This paper describes the design of Seq-SAT - an efficient sequential SAT solver with improved search strategies over Satori. The major improvements include (1) a new and better heuristic for minimizing the set of assignments to state variables, (2) a new priority-based search strategy and a flexible sequential search framework which integrates different search strategies, and (3) a decision variable selection heuristic more suitable for solving the sequential problems. We present experimental results to demonstrate that our sequential SAT solver can achieve orders-of-magnitude speedup over Satori. We plan to release the source code of Seq-SAT along with this paper.