It is incredibly important to make sure your aquarium is properly supported!
Your cabinet support should at the very least be the same size as the aquarium, if not larger. This is to ascertain that all 4 sides of the aquarium are equally supported and not allowing excess pressure to be placed on particular seams. This can cause weak joints and eventually a split, leading to a nasty leak and possibly damage.
We also recommend always making sure your cabinets (and aquariums!) are properly levelled.
An unevenly placed cabinet can place unneeded stress on a particular seam, drastically increasing the chances of a split seam and a nasty leak. The use of polystyrene can be a huge help as it assists in keeping the tank cushioned and levelled as well as providing a slightly softer base to sit on.