Draw a line from your point of departure to your set heading point. The point should be something easily recognizable. A highway junction, a bridge, a distinctive small lake, or an island all might be good set heading points. A good set heading point is also in the direction of your destination and far enough from your departure point that you will be at cruising altitude by the time you reach it.
Mark your set heading point (SHP) on the chart and draw a line from the departure airport to the SHP. Then draw a line from the SHP point to the next point along your cross country. This could be the destination on relatively shorter cross countries or it may be another prominent feature along your route. Repeat this process for every leg until the destination.