Determine the number of sides you want your geometric figure to have. For example, a triangle has three sides and a square has four. There is no limit to the number of sides your figure can have.
Map out your geometric shape (for example, a square) on graph paper. If you want your square to measure 4x4, plot a point at (0,0) and plot the remaining coordinate points. First, go over four steps on the X axis and mark a point at (4,0). Next, go over four steps on the X axis, then count up four steps on the Y axis to plot the point (4,4). Finally, count up four steps on the Y axis and plot the point (0,4).
Connect the points of your geometric shape using a straightedge, such as a ruler.