There are six skills that you can work on with your sim - mechanical, cooking, charisma, logic, body, and creativity. You build up a given skill by doing activities that would promote it. For example, to learn how to cook, you read a book on cooking. Note that while you can slowly learn things on your own, you learn MUCH more quickly if you do it in a group. If you find 6 other people all practicing guitar in a music room, and join in, you'll become a guitar superstar in much less time. So it pays to learn skills in groups!

The highest you get in a given skill is 11 - and your skills degrade over time, to encourage you to practice a bit. The higher your skill, the more slowly they degrade, so it's worth it to focus on one or two skills and get really good at them. Again, just like in real life.

And unlike real life, learning skills is free. Just find a home with a skill object, start using it, and with a bit of time and patience you can be an expert in that area!

The Sims Online Tips, Techniques and Walkthroughs