Add weight to the camera. Lighter handheld cameras will highlight the natural motion of your body while you hold the camera and make the shot look worse. If you have a tripod, attach a free weight to the bottom of the spokes and hold the tripod off the ground. If not, attach the weight directly to the camera using a non-residue tape. Whatever your method, ensure the weight and camera are firmly affixed to avoid damaging the equipment.
Hold the camera against your body, near your stomach. This stabilizes the shot against your center of mass, increasing overall smoothness and control. You may need to kneel on the ground or stand on a platform to reach your desired shot height using this method.
Move your entire body for the pan and tilt motion, not just your arms. No matter how strong, your arms alone don't provide a very stable platform for the camera. Twist and bend at the waist to make the motions, keeping the camera still in relation to your body.
Keep your motions simple. If you want the final shot to look professional, keep the pan and tilt as simple as possible. Shoot from a stable, non-moving location and only pan and tilt in one direction before cutting the shot. If you need additional camera movements, break them up into different shots from different angles, rather than keeping them in one long moving shot.