I get many compliments on the photographs of coins I take. One secret is using natural, diffused lighting. I always set my coins on a window sill with a white sheet of paper underneath, and let the natural light do much of the work. (No direct sunlight as it creates shadows; just using light that comes in). Below are some of my examples I took with my Canon EOS with a 100mm macro lens. (If anyone is interested in me photographing your collection, send me a private message.)
I just took 288 photos (144 coins) for a dealer here in Buffalo, NY. No charge. All he paid for was a jump drive for me to put the photos on and postage to mail it.
Wow, that's a lot of work you're giving out for free. A tip of the hat to you! I just finished a run of many coins at $3 each and I groaned like it was the world's worst job. Rasiel
Your shots are pretty good. Better than many on here, but if you want to raise the bar, check out my web page.