Bioshock > Bioshock Levels > The Museum Gauntlet
This level is simple: You follow a Little Sister on a winding path through the abandoned museum that serves as the Sisters' training center. She is quick on her feet, and you are encumbered by your Big Daddy suit, so be careful not to lose her.
The Little Sister opens doors for you. You guard the Little Sister as she impulsively gathers Adam from three corpses. Fight off the aggressors that converge on you as she works. Hacking the cameras and turrets helps to keep you and your charge safe both from splicers and from the devices themselves. (Now that the Little Sisters are humans again, the security will attack them.)
Remember, without the sea slug in her belly, the Little Sister is vulnerable. A progress bar indicates how much life she has. If, despite your efforts, a Little Sister dies, you can bang on a vent with your wrench to summon another. Near the end you are attacked by a rogue Big Daddy; dispose of the brute.
Finally you reach the elevator that goes up to the lair of Fontaine. The Little Sister climbs into the vent and hands over to you her syringe. The syringe is your chief weapon against Fontaine.
There is plenty of ammo and other goodies, either lying around or in the vending machines around the elevator. You can also backtrack to clean out the dead aggressors for their loot. The surviving aggressors, who regard you as a Big Daddy, will not bother you.
Save your game before you get on the elevator: If you die during your fight with Fontaine without saving your game, you will be kicked back to the start of the game itself.