Avoid timing issues by checking the accuracy of your clock before the start of any observation U.S. Naval Observatory's Time Service Department provides accurate UTC time For best visibility search on a cloudless night when the moon is not out. Many asteroids are visible near the horizon and can be obscured by the atmosphere Searching at high altitudes far from lights will help Asteroid brightness changes as their position to the Sun and Earth changes. Asteroids are often detected when at their brightest and this makes follow up observations difficult. Infrared telescopes detect asteroids from the heat they emit instead of reflected light.
Avoid False Detections
Take at least 3 images and dither the telescope between each. Dithering means to slightly change where the telescope is pointing. Telescopes with motorized slewing make this much easier. Increase your time intervals between images - 30 minutes of coverage for each object at a minimum.