Janet Craig is one of the most popular Draceanas used indoors, likely due to it's ability to grow in low light and tolerate considerable dryness.
The temperature requirements for Janet Craig is a comfortable 75 degrees and the water requirements are low. Dracaenas are one of the plants used in the NASA Clean Air Study and has shown to help remove Formaldehyde.
The wide leaves on Dracaenas can and do accumulate dust. Wipe leaves down regularly with a damp cloth to remove dust. Although most Dracaenas have few problems with pest, occasionally mealy bug and scale can attack the plant.
Yellow and brown tipping of Janet Craig leaves is quite common as they age. There are a number of causes for this.
Allowing the soil to get too dry, even just once in a while.
Using water that is on the hard side. Switch to filtered or distilled.
Using fertilizer at more than half the recommended strength.
Allowing roots to wander out of drainage holes. Unpot the plant, trim off large roots at the bottom of the rootball, add an inch of fresh soil to the bottom of the pot, and then put it back into the same pot.
Allowing the pH of the soil, to get too low (too acidic). Adding some horticultural lime or gypsum to the soil will help reduce the soil acidity.
Once the tips have discolored, all you can do is to trim off the discolored part and take the appropriate remedies mentioned above. This should limit future damage.
If many of the leaves have been removed or look badly trimmed, then you might consider pruning back some of the stems.