Find or decide on the dimensions of the desired sports field. If sports will not be played for official purposes, or if space is limited, field dimensions can generally be estimated or altered without much difficulty. If official field sizes are needed or desired, they can be found on a number of websites, including SportsKnowHow.com (see the Resources section).
Using a tape measure and the desired sports field dimensions, measure out on the field where each line will need to be applied and how long they will each be. Insert a golf tee into the ground at both ends of each line measured, and tie a length of brightly colored twine or thin rope somewhat tightly between the two tees representing each line. This will mark where the lines should be drawn and help to make sure they are as straight as possible when applied.
Purchase, borrow or rent an athletic field line applicator. The Chalk Line Express by Fundex is a useful applicator because it can be used with spray chalk or latex spray paint cans. Other forms of chalk applicators can sometimes be rented from major sporting goods stores. If latex paint will be used to draw lines, sometimes a can or two of white latex spray paint will work as an applicator without purchasing or renting further equipment.
Apply the paint or chalk lines to the field. If using a rolling applicator, roll directly on top of the lines that have been laid out. If using a spray paint can, carefully spray directly over the top of the twine or string, holding the nozzle about 6 inches from the ground. Chalk lines will be immediately ready for use. Paint lines may take at least a half hour to dry.
Remove all golf tees and twine from the ground. These could be dangerous if tripped on during a sporting event. At this point, the field should be ready to use for the desired sport.