I've been using A-10 for a while now, and finally decided to join since I feel like I finally have some tips to offer. Anyway, the thing that has worked the best for me is (1) setting gain correctly (Sometimes I test in on civilian traffic on the roads) and (2) Switch between WHOT, BHOT and CCD quickly, as each one is useful in different circumstances at different times. Mapping the 3 different modes to an easy to use keyboard or joystick button helps. Just keep scanning and flipping modes.
Also, if you really need help, use labels to practice.