Keeping a Sim's social meter up can be a nightmare. A good way to avoid this is to make the outgoing trait as low as possible (mine are usually zero). A shy Sim may take longer making friends, but an outgoing Sim constantly needs companionship (which takes up a LOT of time). With this trait at zero, once you fill up the Social meter, you can go three or four days without a visit from ANYONE!

Also, for me, the most difficult ability to fill is Body. If you make your Sim's Active trait high, they'll take to the treadmill like a duck to water. You can also guarantee that watching the Action channel on the TV will always provide some fun. Making Active high works well if you want your Sim in the military.