Instructions
Open the Sims 3 game by double clicking on the Sims 3 icon that should be on your desktop, and clicking on the "play" button on the left hand side of the launch page. Click on your Sims household to begin the game.
Press "ctrl," "shift" and "C" buttons at the same time. A command box should appear on the top of the screen.
Type "testingcheatsenabled true" without the quotation marks and press "enter."
Go to the Sims household mailbox and press "shift" while clicking on the mailbox at the same time. Click on "make needs static."
Pick the skill you'd like your Sim to level up and have them perform the necessary activity. For the Athletic skill, have the Sim work out in the gym. For the Charisma, have the Sim practice their speech in the mirror. Make the Sim read all of the cooking books to raise the cooking skill. Have the Sim fish at a pond to raise fishing skill. For the gardening skill, have the Sim read all gardening books. Make the Sim play guitar for the music skill. Read all handiness books for this particular skill. Let the Sim play chess for the logic skill. Paint numerous paintings on an easel for the painting skill. Write several books on the computer for the writing skill.
Fast forward the game at full speed by pressing the number "3" on your keyboard. Allow the game to stay like this until the skill has been mastered completely. For skills, such as painting and writing, you will have to pause by pressing the number "0" on the keyboard and have the Sim start a new painting or a new book after one has completed, and fast forward again. For skills that require them to read, purchase the corresponding book for each level. Once one book is done, pause and select the next book to read.
Press the number "1" to make the game play in normal speed once the skill has been mastered. Go back to the mail box and press "shift" while clicking on the mailbox. Click "make needs dynamic."