Your taxi speed should be slow and under control. Fast taxiing is not only unprofessional but also dangerous. You should be able to stop the aircraft within a short distance at any time. Use differential braking (left and right toe brakes) to steer at low speeds, and use nose wheel steering if available on your aircraft. Keep the propeller in fine pitch (high RPM, low throttle) during taxi.
As you taxi, listen carefully to the frequency. Other aircraft may be calling for clearance, reporting their position, or being given instructions. This helps you build situational awareness. You may also hear radio calls from Tower, which gives you early warning of the traffic situation and wind information.
If you lose track of your position while taxiing, stop the aircraft immediately and inform Ground Control. Say "F-ABCD, unsure of position, request guidance." This is professional airmanship, not a failure. Controllers expect this to happen occasionally, particularly at complex aerodromes. The controller will provide directions based on your last known position, radar location, or will ask you to describe what you see (a hangar, a building, other aircraft nearby). Stopping to confirm your position is far safer than continuing when uncertain.