When levelling up skills, there are lines that you need to complete – each line can be considered a level, or sorts. If you are painting, for example, the more you paint, the more lines will be completed. Eventually, you will reach a new level and unlock a new skill item. Levelling up skills is, in addition to completing quests, the way to progress through the game and unlock everything available.
Visit the Skills section of the shop to see items that can help you perfect skills. The golden icon indicates the relevant skill.
Skills in The Sims Social include Art, Cookery, Music and Writing. You can buy items for each of these to increase skills. Each time you level up, you get a host of Simoleons. Make sure you are Inspired while working on your skills for maximum reward.
When levelling up, you need to have certain items to be able to progress to the next rank. Some these can only be received by interacting with your friends in game.