You can soften up the soap scum that collects on the sides of your bathtub with baby oil -- a generic variety will do just fine. Mix 1 part baby oil in 4 parts water. Next, use a funnel to pour the mixture into a clean spray bottle and spray the sides of the tub (but try not to spray directly on the bottom of the tub). Give the solution a few minutes to loosen the soap scum and then wipe it away, using a clean, damp cloth or sponge.
To remove any oil that may have gotten on the bottom of the tub and made it slippery, wipe it down with a sponge soaked in white vinegar. And, as always, be sure to use caution when you are entering and exiting the tub.