Just unfocus your eyes to detect movement where nothing else is moving. Be sure you re upwind. Neotropical birds tend to go around in mixed flocks. The best tactic for seeing them is to determine the flocks direction and get ahead of them. That way, you are still and have maximum time to get the field marks.
Colors can be tricky.
Not just the chatting as you walk the trails. Some fabrics are much quieter than others. Olympus has the quietest shutter we are aware of. In the tropics wearing perfume, deodorant, aftershave, etc., can work against you - it s attractive to biting insects, as is the color blue. Even if you are an experienced birder, in the neotropics expect the unexpected.