Make sure you buy actual Aquatic plants - - if you buy them from Petsmart/petco/any pet store and they are in a plastic container WITH OUT water then they are not aquatic regardless of what the packaging says. True aquatic plants need to be kept submerged - little "Crystals" along their roots are not going to preserve them. If you buy these and put them in your tank, they will rot and foul up your water.

Great very-low maintenance plants are java moss, java ferns, and water wisteria. You should be able to keep these alive with no problem as long as you have some lighting on your tank. (nothing crazy - just your standard tank's light)