Clean the foundation with a broom prior to laying the first course.
Wet down the foundation where you are laying the first bricks.
Mix mortar in a wheelbarrow.
Build your two corners first before you start on the first course. Just the first two courses in the corners need to be done.
Lay down your guide lines from the first course of each corner. You will have one brick on either end since you built the corners first. Lightly tap a nail on the top center of one brick. Extend the line across the course to be built to the other corner and secure the line with a nail. This is your level guide for your course. Secure another line by tapping a nail into the side of the brick and extend this one to the side of the other brick. This line will keep you on a straight line.
Lay mortar down with a trowel for the first few bricks. Each joint is 3/4 inches wide.
Follow the guide lines but as you move across the course check each adobe brick for plum. Use the long level to check level over several bricks and the short level to check individual bricks.
After the first course, start on in the corner and overlap the first brick by 50 percent. Repeat this process until the wall is done.