Install a shallow French drain. Also called a curtain drain, it extends horizontally across your property, directly uphill of the area you want to dry out. It intercepts water and channels it around the soggy spot.
This type of drain doesn’t have to be very deep -- a common size is 2 feet deep and 1.5 feet across. Where the drain passes through areas with trees or shrubs, switch to solid pipe (not perforated) to reduce the risk of roots growing into the piping and clogging it.
Install a deep French drain. Also called a footing drain, it runs around the perimeter of the house at the footing level and intercepts water before it can enter your basement.
It’s easy to install during house construction, but much more difficult and expensive to add later. If you have tall basement walls, you may have to dig down quite a ways to access your foundation footing. Also, there are probably landscaping, decks, and walkways that will have to be ripped out in order to install the drain, adding to the cost.
If you’re building a retaining wall, add a French drain behind the first course of stones or blocks.
Otherwise, water moving down the hill will build up behind the wall and undermine it. The pipe should rest on the same compacted gravel base or concrete footing that supports the wall.
To protect the drain from clogging with silt, drape landscape cloth across the base or footing and up the slope before adding the pipe and drain gravel. Near the top of the wall, fold the cloth over the top of the gravel, and top with several inches of soil.