You really need to relax with the grass on grass bits. The tiles are fun to use to give depth but abusing them makes levels look incredibly ugly. A lot of LATs that were around for a while now associate them with the horrible level trends of 2002-2003, where people would just out-right abuse the tiles.

Use them to compliment areas, not as filler.

You've got a decent start, just practice on detailing and style.