Study every skill and get them as high as they will go, then start to work in any desired field. No matter what field you work in, you will receive one promotion per day. Your Sim's happiness level and friends count affect it in the later stages. This works well when you are using the money cheats. However, it is possible to do this without cheating by painting pictures and selling them; and creating potions and drinking them (as this will increase all your happiness levels, except sleepiness and hunger, saving you time). Every once in awhile, use a day or two to call a friend and talk to them all day. This will help you get family friends faster.