Do not keep lots of pen accumulated on your desks and this will give an ugly look to your desk. Throw away all the pens except two or three. In case the pen does not have a cap then just toss it.
Avoid the free caps at conferences and internal office events. Resist the temptation of taking the cheap pens, stickers, free magazines, brochures, postcards, and anything that will choke your drawers and desk.