hi, interesting study of the insects, good work for first time... well, dunno whether im "qualified" to say this, but i have some opinions from personal experiences and also what i see...
first, i think good close-ups should be razor sharp, not easy to achieve cos aperture needs to be big enough for dof and yet shutter speed must be quick enough to freeze those little movements of the subject, provided there's ample lighting! blah blah. but that's how u get a good shot lah.
second, one thing i notice and often do is to get obssessed with the subject, with the zoom, with getting a razor sharp pic and neglect the 1.composition, 2.lighting and 3.framing. and when you take too long to consider, subjects such as the dragonfly may change position. that's why really good close-up shots aren't really easy. even if one gets a razor sharp close up, but composition is plain, then it ends at the "sharp" part, and becomes a sharp record shot, without much aesthetic value.
just some humble opinions and observations, hope one day i can achieve some nice close-up shots myself hehe, still trying. cheers!