To lay bricks correctly, you must spread cement mortar in a mud bed with a trowel, as well as smear it onto bricks so they bond together. This trowel is used to scoop up mortar from a mortar board and spread it out in a straight line into the mortar bed, which is 2 to 4 inches thick and 4 inches wide. The trowel is also used to smear mortar onto the ends of each brick before pushing the brick into the mortar bed and sticking it to other brick end to end.
Bricks are always staggered to increase the strength of the brick wall. To do this, each brick row is installed so that the end of each brick lands in the middle of the prior brick row bricks. This is called a "running bond brick pattern." Although there are other patterns, such as Flemish bond where the bricks alternate between whole and half bricks, all patterns stagger to increase the brick's structural integrity.
Bricks must always be leveled along the length of the brick, as well as across the brick. After the brick structure has reached 4 feet tall, it must be plumbed as well. Generally, bricks are laid out three or four at a time along each individual course or brick run and leveled with a 4-foot level. If the bricks are unlevel, then tapping the level with the handle of a mason's trowel will help set them level.
When laying a larger number of bricks at a faster pace, masons use a nylon string and line blocks. Two ends of the brick structure must be constructed first to have a surface onto which to hook the line blocks. The nylon string is attached to the two line blocks, one at each end of the wall, and stretched along the wall project. By placing the string at the top of each brick on each end of the wall, you can follow the string when laying along the wall, which will allow you to lay them straight and level.