Replace the caps to pens whenever they are not in use, even while a drawing is in progress. Not only will the ink of uncapped pens dry, the Gelly Roll pens' tips may develop a clog due to dried ink.
Dip just the tips of the pens into a pen cleaner solution when finished using. Pen cleaner solutions are available from pen and ink manufacturers. The solution will keep the ink at the pen's nib viscous. Touch the tip to a paper towel before using the pen again to remove excess solution.
Place the pens in an upright pen holder with the tip sides facing up. Placing the pens facing up will prevent the ink from pooling inside the pens' tips.
Keep pens in a location with moderate temperatures. Do not place them in freezing rooms, leave them outside on hot days or place them next to hot objects such as lamps or stoves. High temperatures can cause the ink to become extra runny or dry out. Cold temperatures can cause the ink to congeal.