i agree with a black background. It would make your plants pop out!
i use the very basic method of the rule of thirds to decorate. I am not sure how big your tank is, but take a 10g for example. At the 1/3 or 2/3 mark in the tank i put my focal point, which would be 6 2/3 inches from either end of the tank. You have the awesome driftwood, and the to broad leafed plants that all seem to draw the eye. Unfortunately it draws you to two ends, spiting your focus. If you rearranged and put the broad leafed plants around or near the driftwood, it would draw your eye to one place. the water sprite would make for a nice background and filler around your focal point.
Keep up the good work!