I am no expert, by any means. But I have taught myself a lot, learned a lot from bloggers (Glorious Treats, especially). I manage to take pretty good pictures with my cell phone camera and a few simple setups. I do not use any expensive equipment. Just whatever I have at home.
1. Lightbox. I have made my own lightbox out of cardboard and tissue. It works pretty darn good. For good macro (up close) photos, this is a must.
2. Of course, sunlight is always best, but since I am often taking my photos after late night decorating sessions or early in the morning, sunlight isn't always possible. So, I keep my lightbox open to the south window. In addition, I have lamps with "daylight" light bulbs in them that I use to light the box. I have one on each side and one I have jury rigged to hang over the top.
3. Again, I use my cell phone camera to take the pictures, but I do take advantage of the settings. Settings I use a lot are the Exposure Value (usually opened up all the way, since I am indoors), Focus Mode and White Balance. I never, ever use a flash. Ever. The best way to get to know how each of these work is just to play with them.
4. Props. For a good portion of my pics I just use white poster board. Recently, I have started using scrapbookers paper and also wrapping paper as backgrounds. I use coupler rings, espresso cups and all kinds of small, hideable things to prop up my cookies.
You can take a look at some of my photos at www.facebook.com/sisterteresascookies. I am no professional, just a hobbyist, so please take that into account, but I have found that the photography of my cookies can either add to or take away from all the hard work I did decorating. Let me know if you have more questions. Again, Glory at Glorious Treats has some awesome advice.