It is important to keep laminate clean, as dust, dirt, and sand particles may scratch the surface over time in high-traffic areas. It is also important to keep laminate relatively dry, since sitting water/moisture can cause the planks to swell, warp, etc., though some brands are equipped with water-resistant coatings. Water spills aren't a problem if they're wiped up quickly, and not allowed to sit for a prolonged period of time.
Adhesive felt pads are often placed on the feet of furniture on laminate floors to prevent scratching.
Inferior glueless laminate floors may gradually become separated, creating visible gaps between planks. It is important to "tap" the planks back together using the appropriate tool as gaps are noticed in order to prevent dirt filling the gaps, thus making it more difficult to put into place.
Quality glueless laminate floors use joining mechanisms which hold the planks together under constant tension which prevent dirt entering the joints and do not need "tapping" back together periodically.