Ten steps to a dry basement:
Note that Number 1 is at bottom!
2. Try going down ten steps into someone else’s basement where they took time and trouble to find out what causes and practical guaranteed remedies were.
3. Determine as precisely as possible major point of entry of seepage.
4. Examine exterior area for sources of water such as loose soil, reverse grading toward house instead of away from it, drainage from downspouts or higher ground areas, plumbing or pipes- especially if they were installed after original construction of house, run-off from roofs and gutters.
5. If any of these conditions are suspects, and you undertake fixing situation, monitor basement in usually wet areas to see if there has been any diminishing effect.
6. If so, try more of same.
7. Assuming wet problems are what are normally called ‘high water table’ or hydrostatic pressure, look into installation of a ‘pressure relief system’ or interior French drains.