Ken, I take photos of anything that moves and anything that doesn't. I don't trap moths, but I do photograph them as and when I see them. In fact I don't interfere with insects (or whatever) in any way. If I get the photo, great, if I miss it, well there is always something else that will come along.
I always try to look at other people's tips: there is always something that someone else does that is helpful for improving one's results. As you say, look at other people's photos too. I would also add that one should look with a critical eye at one's own photos. Try to analyse what went right or what went wrong.
One thing I would add to the list (unless it is there and I am just not seeing it) is in (scientific) record shots take at least one photo with a ruler/scale alongside - or press something else into service. I used a camcorder alongside a White Witch Moth which game me a fairly accurate wingspan of 8.75 inches, 222 mms.
I have to say I don't bother with a grey card these days. I used to use one for film from time to time when it was difficult to adjust colour balance, but it's quite easy to adjust in digital, especially if shooting in RAW - as long as there is a single light source. Multiple light sources of different colour temperatures will always cause problems. I agree though for an accurate scientific shot, a grey card is sensible.
Budget: there is a truism in, at least, some photography that the bigger your budget, the better will be your end result. That said, most photos are viewed at around 1000x800 pixels and so much potential quality is lost. In fact it is easier getting acceptable results from a camera with a small sensor, as the depth of field is so much greater than for a camera nearing 35mm or larger.
In general with digital it is better to slightly underexpose. Dark areas can be lightened, but there is no detail at all in burnt out highlights. When it is possible on the camera/flash I normally have the flash "turned down" by about 1 stop. I find this better for most situations - 1) as only light source 2) as main light source 3) just acting as "fill in" to lighten the shadows.
Now for one of my bug-bears. Many photos are called "macro" which are nowhere near being such: in fact they sometimes don't even qualify as being "closeup". Often cameras/lenses have a macro setting which is actually about 1:3 - closeup but not macro.
Ken, thanks for your tips, and I'm sorry to have rambled on (though I've tried to keep it down).
Dave.
