If you aren't able to shoot outdoors (in the open shade is best for product photography) using a little tissue in front of the flash as a diffuser- especially if it is several inches or more away from the flash - will help soften the light and make it look more natural.
You might also want to pick a neutral background - not too dark and not too white. That will help separate the item you are shooting from the bkgrnd.
Automatic cameras see a black background and try to compensate for the darkness by making the picture lighter - sometimes WAY too light. A white background shot taken with an automatic camera will often come out looking too dark because the camera sees all that white and tries to compensate - making the shot an 18% average grey.
Not sure about the spots in some of the shots - looks like white dust from something.
Nice modeling by the way!