Foot-based gestures have recently received attention as an alternative interaction mechanism in situations where the hands are pre-occupied or unavailable. This paper investigates suitable real-world mappings of foot gestures to invoke commands and interact with virtual workspaces. Our first study identified user preferences for mapping common mobile-device commands to gestures. We distinguish these gestures in terms of discrete and continuous command input. While discrete foot-based input has relatively few parameters to control, continuous input requires careful design considerations on how the user's input can be mapped to a control parameter (e.g. the volume knob of the media player). We investigate this issue further through three user-studies. Our results show that rate-based techniques are significantly faster, more accurate and result if far fewer target crossings compared to displacement-based interaction. We discuss these findings and identify design recommendations.