Things You'll Need
Spade or shovel
Soil compactor hand-tool or plate compactor
Whether you decide to build a brick, flagstone, concrete or paver patio, you need a somewhat level surface if you plan to use the patio as an outdoor sitting area. A very slight slope on the finished patio's surface will provide better water drainage to prevent the substrate material from washing out and causing dips in the patio surface. Prepare a patio surface on a sloped area of your property using only a handful of tools to create a gentler slope for the finished patio.
Excavate the soil in any shape, length and width you desire of the finished patio, using a spade, shovel or backhoe. Mark the shape onto the ground if necessary and begin excavation at the lower side of the patio site. Continue excavation, removing additional soil as you reach the higher side of the patio site. Keep the bottom of the excavation site close to level as you dig. If a small slope exists, it should slant with the slope of the surrounding land.
Shape a slope into the bottom of the excavated area if one does not already exist. Slant the slope from the back of the patio site to the lower, front side of the site, allowing the slope to drop 1/4-inch for every foot of the patio's width between those two points.
Measure the slope, by tying a string to a stake inserted just outside the lower end of the patio site. Extend the length of string to the opposite edge of the patio surface. Use a level to adjust the string's height on the stake so the string hangs taut and perfectly level between the two surfaces. At the lower end, measure the distance between the string and the ground and divide that number by the patio's width to ensure the patio slopes approximately 1/4-inch per foot.
Compact the soil at the bottom of the patio site using a soil tamper hand-tool or plate compactor device. Walk the device over the patio site or pound the hand-tool against the soil throughout the patio site until the soil is hard and resists settling under your weight. Adjust the slope of the area again, as necessary.
Smooth and slope any additional layers of sand, gravel, concrete slabs or crushed stone used to create a base for patio construction to match the slope of the patio site. Build retaining walls along the sides of the patio you had to excavate the deepest to prevent the soil from eroding onto the patio surface.