How to make a Sims mod?

I’m interested in creating mods for The Sims and would like to know how difficult it is. What skills do I need to learn? I want to create furniture models to make the game more realistic. Do I need advanced modeling skills and a strong computer background? If I’m not proficient in 3D modeling, can I use a 3D scanner to scan real objects? (By the way, has anyone used Revo’s POP3 3D scanner? How is it? Does it meet the needs for 3D modeling?) My initial plan is to scan some objects around me with a 3D scanner to get 3D models, modify these models, and then import them into the game. This might sound a bit simplistic, so I’d appreciate any recommendations for websites or videos to help me learn how to create mods and what software I need.