In an attempt to improve the quality of photographing my paintings, I finally bought a cheap set of lightings and a little device to measure the intensity of lights so the light hits evenly on the paintings. I guess ideally I need four, instead of two, but with the 3 feet x 3 feet size I was able to get pretty even lighting throughout. It's a trial and error, even though there are lots of self help videos and other instructions online, but "do it on my own and see" is the only way to get this right.
Below is the first shot with this lighting system. It's totally uncorrected and untouched, except that I cropped it. It's not too bad.
The next step is to buy a decent digital camera... I am using an "indecent" camera now. One stop at a time. I can't make up my mind on which camera to buy. I have never owned a Canon camera, so I most likely get PowerShot.