Put on a long-sleeved shirt, long pants and shoes that completely encase your feet. Wear work gloves and plastic safety glasses. Cover your mouth and nose with a disposable paper mask. Wet concrete can stick to your skin and cause burns, and breathing in fine particles is dangerous to your lungs.
Set your wheelbarrow on a level surface so that it stands up straight. Make sure that the interior is clean and free of dust, dirt and other debris.
Add six shovel spades full of gravel, four shovel spades full of sand and two shovel spades full of cement powder to the wheelbarrow. Use the shovel to mix these dry ingredients together completely. Check that the consistency of the mixture is uniform throughout.
Fill a standard five-gallon bucket with 2-1/2 gallons of plain water. Pour approximately 1/4 of this water into the wheelbarrow.
Mix the water into the concrete with the shovel. Pick some concrete up from one side of the wheelbarrow with the shovel spade, move it to the other side of the wheelbarrow and drop it back in. Repeat several times. This folding motion is similar to the technique used to mix cake batter, since you are also adding air to the concrete.
Add another 1/4 of the water to the concrete and mix it again using the folding motion. Continue adding the water in quarters until it is all incorporated into the concrete and the concrete is well-blended.
Use your concrete as desired.