Had a nice little foundation leak during the last rain storm. Installed a drain line last fall to divert two downspouts and front walkway run off away from the house which helped a lot. Front walkway and a big retaining wall next to it ultimately need to be removed and reinstalled with proper grading and drainage. That's going to be a huge and expensive project so for now I'm just replacing all the worn out concrete sealant and hoping for the best.
but you also need to exchange the air inside often, so you need ventilation too.