Yes you should only be shooting at night, with the rest of the lights in the room off, in order to keep the lighting consistent. Also let your bulbs heat up 5 minutes or so before you start shooting so they reach full brightness.
I use a 2 second delay when I shoot, because your finger might wiggle the camera when pushing the shutter button.
If you are shooting pots of different colors, try "bracketing" each shot. Take three different exposures, the one in the middle being the one you think is correct. Once you get them large on your computer screen, you might find that the lighter or darker one is better. Hardly takes any more time to bracket while you're shooting. But if you get the photo on your computer and decide the exposure is wrong, it's a lot of wasted time to shoot the pot again.
It doesn't matter if your photos are 72ppi or 300ppi. It's the overall number of pixels that matter. So just take the largest photos your camera will take.