How your dragons behave will largely be up to how they are built biologically, especially since there isn't a supernatural element. This is obviously up to you, but here is a quick rundown of the typical lifestyles of these types of animals based on organisms that actually exist (or used to exist).
Endothermic or Ectothermic?
Here's really your largest factor in terms of general behavior. Endo and ectothermic refer to how an animal gets its body heat, and, in general, this affects how they act. Think of your run-of-the-mill reptile for instance. Reptiles (for the most part if we aren't talking about anything extinct) are ectothermic, which just means that they get their body heat from an outside source. In reptiles, this results in an animal that is less active when the weather is cooler, which lends itself to a lifestyle of basking and waiting for prey to pass by, as you mentioned. Mammals, birds, and possibly non-avian dinosaurs however are (and were in the case of the dinosaurs) endothermic, meaning that they generate their own heat, which lends itself to a more active lifestyle.
Hip and Leg Posture
This may not seem all that important, but it really is. Many of the endothermic and active animals I mentioned early have a very particular hip structure, which allows them to stand directly upright (like a human being for instance). This stance gives them an advantage over animals with sprawled legs, allowing them to run faster and for longer. This would again contribute to a more active lifestyle.
The exact form of flight you want your dragons to use may also hint at a likely lifestyle for them. Birds (and likely the ancient pterosaurs of the Mesozoic) have extremely developed brains to help process the overload of information that comes with powered flight. Not only that, but powered flight takes a lot of energy and endurance, hinting at an endothermic animal (though there may be outliers). If your dragons have powered flight, I'd say its pretty likely that they would follow this trend. However, there are other avenues to take here. If you aren't as on board with an active lifestyle, two types of endothermic animals have also taken to the air: the draco lizards (Draco) and the flying tree snakes (Chrysopelea). Both of these groups of animals have developed "wings" made of ribs with specialized skin and muscle forming a sort of parachute that can be extended at will to glide between high places like trees. So, if your dragons need to be more inactive and able to fly or glide at the same time, "rib wings" might be perfect for their snake like builds, as long as they can find a high place to leap from.
If your dragons are ectothermic and slink around on sprawled legs or glide on draco lizard like "rib wings", they would seem to be more likely to hunt in a less active fashion, striking out in short, quick bursts of speed. However, if your dragons are endothermic, with carefully controlled flight, then I'd say a more active mode of hunting, such as dive bombing or long distance running is pretty likely.