It depends upon how much of a moisture problem you have. Water pouring though cracks, flooding in the basement, high water table, water puddles coming through the floor, drops on the wall or floor, a slight dampness, apparrent dampness on the walls, dry walls with high humidity, etc. It is hard to recommend a treatment without knowing the extent of the problem.
Treatment ranges from yard drainage, french drains, sumps and sump pumps, fixing walls, fixing floors, coating the wall and floor with a liquid sealant or plastic, etc. Your best sealing method starts on the outside. Good luck.