Gah, insects.....the hardest thing is making sure the little bleeders keep still long enough. A tripod is pretty handy when trying to get a close in shot with a full macro lens, as the image is displayed on the sensor as 1:1, in other words if it is a 10mm bug it will be 10mm on the sensor, making camera movements more noticeable. As for composition, well you could try setting a 'trap' and see what comes along. Set the camera up with the tripod and compose the shot using a half eaten apple or something similar, then it's just a case of waiting to see what comes along for a chomp on the apple.
Don't be afraid to get in good and tight with those crops, but not too close as it starts to break the image up into individual pixels. Number 4 is a good shot but possibly slightly over cropped. Try and get the re-size correct for forum posting, if you leave it up to the inbuilt filter in the forum it will soften the image slightly, the last thing you want for good macro shots. If you click on your 4th image and view it how it was meant to be you will notice a bit of a difference, the shot appears slightly sharper, though it will highlight any over eagerness with the sharpness slider in Photoshop.