I painted the sand a light tan and the water I painted a glossy tan. With a very high gloss. Water often is murky or silty and so it can be brown, or tan colored. By painting a dirt color with a gloss finish this can be replicated rather well for the wargame table.
Look for hobby projects everywhere you go. Cake decorating stores sell plam trees and other plantlife. I ordered a gross of them, 144 two packs, and got them for almost nothing. Not only were the two packs really cheap, by ording a gross of them, the cake store cut me an evey better deal. Most of the others were mounted on old CDs and DVDs that were due for recycling anyway. Epoxey or a hot glue gun are good methods to attach them to the base. A little paint, some flocking and you are done.