Whether you need to amend that soil or not depends on what is has now.
How much organic matter is in that soil?
How well does that soil drain?
How well does that soil reatin moisture?
What does that soil smell like?
How is the workability (tilth) of that soil?
What kind of life is in that soil?
What is the soil pH?
What is the nutrient balance?
Start by contacting your state universities Cooperative Extension Service about having a good, reliable soil test done so you know the pH and major nutrient levels and then dig in with these simple soil tests to find out more about your soil,

1. Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

Once you have this information at hand you will know what needs to be done to make your soil into a good, healthy soil that will grow strong and healthy plants.

First thing is to make certain that none of the loose soil gets washed away when it rains. This is one of the things that are forgotten about when people till their soil in advance. Tilling of any type will raise the surface above the surrounding area which will make the rain drain off many times with your soil and/or mulch. A barrier around your tilled area may be useful to keep your soil in place. Similar to what construction crews do.

Someone made a joke at a garden club lecture this spring after one of our heavy rains that after the talk the people could go looking for the soil and mulch that had been washed away. Since most had had something washed it was funny but the amount of soil that is washed into streams and rivers each year is not.