Let me explain a little about my theory and practice of downloading Sims... I download Sims for their facial geometry, not how pretty they're dressed or made up. That's why my downloadable Sims wear Maxis clothes, hair, and makeup.
These Sims are not complete, playable Sims. They are packaged BodyShop Sims, ready to be used to make your new Sims.
To use my Sims in your game, Create a Family, Add a Sim to your new family, set the gender appropriately, then click the import button (looks like 6 little Sims, next to the Random (dice) button).
Some EP/SP content used. I've tried to note this, but may have overlooked things if I used the "random" button as the base for the Sim. Please comment if something doesn't work in your game and I'll try to resolve it.