Water coming into Basement
The previous posts provide a good idea where to start. As noted, address all outside drainage issues, which means make sure grade leads downward away from your house at a minimum of 2 percent, gutters are at least five feet from the house where they empty. If this does not address the water leakage problem, a perimeter drain is a good second step. Actually, I like a perimeter drain regardless of how well graded the house is.
Installation of a perimeter drain after the house is constructed is a lot of work. You need to excavate a trench at least a foot below the slab elevation all the way around, install perforated pipe, surround with crushed stone and filter fabric, and connect the pipe to the sump pit. Unless you are very fortunate and can drain the groundwater via gravity to a stream, storm sewer, or low point well away from the house. If you cannot go gravity, you need to install a sump pump with associated piping, connected to the storm drainage system (never the sewer system).
A lot of work and money in a perimeter drain system, best to try correcting exterior drain problems first.