Drill with a licensed driller and yield-test the well

Drilling is specialist work, and the yield test tells you whether the well can really meet demand at peak times.

How

Use a certified or licensed well driller, as US EPA advises for new wells, changes and well closures. Get the well permit first if your area requires one (legal module).
Ask for a written well log: depth, casing, grout seal, water strike levels and static water level.
Require a sustained yield test. New York State requires yield testing for new drinking water wells and targets a sustained yield of at least 5 US gallons per minute (about 19 L/min) for a home, which it estimates covers a typical peak of two fixtures running at once.
If yield is lower, plan storage. New York recommends 100 to 300 US gallons (about 380 to 1,140 L) of storage for wells yielding 1 to 5 gpm, depending on bedrooms, and does not recommend wells under 0.5 gpm for a home.
Remember casing storage: a 6 inch (150 mm) well holds about 1.5 US gallons per foot (about 18.6 L per metre) of water column.
Record drawdown at the test rate. You need it for the pump head calculation.

Safety: Never enter a well pit or dug well: low oxygen and gases can kill. Keep children away from open boreholes.