I am not all that great at taking knife pics, but I do try to experiment alot with it. Im not sure what specific problem you are having, but here are a few general things I have figured out. I probably wouldnt have figured them out all that quick, but a few people here have givin me good advice, so I am mainly just passing it on.
On knives with shiney blades, dont let the camera flash directly at it. Without special lighting equipment, I have found the best way is to shoot the knife at a fairly extreme angle. Here is a shot of a satin finish blade. Only had about a minute to set it up, but I used a tooth pick to keep the knife resting at about a 45 degree lean. I kept the camera at an angle, and tried to keep the flash aimed above the knife, so it would not hit directly on the blade, which would cause it to look veryu dark in the picture. Again, this was no access to special lighting equip.
http://albums.photopoint.com/j/ViewPhoto?u=110070&a=805643&p=18059230
Bead blasted knives seem much easier to do. I still try to not let the flash hit dead on, but you still dont have to be to picky about it. Here is another quick shot of a knife. The wood I had it on was more reflective than I though, and im not good enough with the software to fix it.
http://albums.photopoint.com/j/ViewPhoto?u=110070&a=805643&p=18101046
Here are some of my other knife pics, not great, but I am learning, as are you. Hopefully this can give you a few ideas and even help a little
http://albums.photopoint.com/j/AlbumIndex?u=110070&a=805643
You also might ask James Mattis, he does great scans.
Also, as I said, people here have given me a few tips and hints on what to work on, so im sure you will get plenty of good advice. Keep practicing. Trying to get better is half the fun
Richard