Because soil types aren't always consistent around the yard, its a good idea to test several samples. There are several easy, inexpensive ways to determine just what type of soil you have. First, take a handful of moist soil and feel it. Rub some between your fingers. Sandy soil is rough and gritty and breaks up easily.
Clay soil is sticky and feels like plastic.
Silt is the middle ground, with much smaller particles than sand and it feels slippery when wet. A heavy clay soil will form a solid lump that is difficult to crumble when it's squeezed together. It's hard to get sandy soil to form a lump and it easily crumbles. Another easy way to check the soil is with a quart jar filled about half way with a sample of your soil and then topped off with water. If you have it, add a teaspoon of Calgon.