There are many ways to attack this problem depending on the type of foundation, depth into the grade, amount and height of ground water (watertable) and runoff.
Regardless of poured concrete, concrete block or stone "rubble" wall constuction the use of a sealer, like Dryloc, is a must. Of coarse the best results are sealing a poured concrete wall. I have seen unsealed poured foundations 6 ft into grade that are dry as a bone and also ones that at 3-4 ft sweat, periodically seap or even flood due to groundwater and runoff conditions.
Waterproofing a wet foundation from the inside is a difficult project and many time futile. It is like patching a leaking boat w/ bandaids from the inside.
Some of the first steps to take is to change any rain/ gutter and downspout runoff. Extreme cases of exteme watertable will require a sump pump. The use of a pump would be good insurance even for that ocational rise in groundwater.
Rubble walls and some concrete block can be the most difficult to deal with if extreme water conditions exist from time to time. Even the best repairs to these type of walls and proper sealing, can still have future leaks due to continued settling and movement of the stone/masonry. I am basing much of this from considerable work on foundations in New England where some homes seem to almost been built into the water table.
Chronic leaks at bulkheads and under existing concrete patio slabs can be slowed or solved by hydrolic cement repair. This can be quite $$$ and should only be performed by a proven contractor.
Some talk of perimeter drains. Do use care if this is considered as part of a solution. Perimeter piping and gravel can act 2 ways. You can inadvertently end up with more water under heavy wet conditions from water filling the gravel "moat" that has been created. Heavy rains and dounspout runoff shed better with good backfill compaction. Of coarse any rising water table due to rain can really only be controlled by a sump pump. Hopefully yours is not the extreme case.
One note to finished, studded walls and any wall board especially when insulated. If high humidity or moist conditions still exist the use of any visqueen/ plastic behind the wallboard can cause mold/ mildew problems.
If you don't or can't have a totally climate controlled basement enviornment, whether by HVAC or at least dehumidifiers, any sort of air circulation during the damp periods will help tremendously. Of coarse any air exchange/ ventilation can created the other "evil" with dust.
Just like to throw some of this info out there hoping it can help for those with some of the real serious issues. Most preparing basements for the "train room" will never see many of these extremes.
