Thanks for writing! The best thing you can do for this type of soil is add organic matter, such as compost, peat moss, shredded leaves, etc. These materials will help the soil absorb a lot more moisture and nutrients. But the great thing is that also help it drain well during wet periods, so your plants shouldn't suffer from wet feet.
In many areas you can find large quantities of organic matter at little or no cost. For example, many municipalities have free compost piles. Or check with local stables about getting quantities of aged well-rotted manure.
Senior Garden Editor, BHG.com