I've just stopped using a second monitor due to starting to play online more and the NVG problem was really annoying me. I thought it would be more difficult to spot targets but it isn't much harder. Look for dust on moving vehicles and smoke and tracer from units that open fire.
I do use a 37" LCD HC TV and using Trackir also makes thngs a lot easier.
As others have said take your time, go in slow and don't enter an area unless you feel it is fairly secure. Your wingman is also a god send, use recon and listen to what he says, he's your best warning when a SAM is fired at you.
I've switched to the ARMA 2 sound mod as well as you can here when bullets are hitting you. I couldn't really tell with some of the other Mods.
When you are targeted by a laser make a note of where it came from break off and reposition then you can look for what was targeting you.
Switching labels off not only makes the game more realistic and challenging but it will improve your frame rates.
Have fun and keep it as realistic as you can:)