Most everyone gets fluorescent lights for their first planted tank. Generally a single bulb, like a 15 watt for a 15 gallon tank. The aquarium books generally claim that most plants need 1.5-3 watts per gallon, and while others constantly argue that wattage is not the issue, it's pretty darn expensive to get better lighting.
A lot of sites mention using "reflectors" for your aquarium. These apparently reflect light that would otherwise shine onto the top of your hood, or whatever. "reflectors" are made of different materials, but are always almost as expensive as putting another light fixture on top of the aquarium. Also, many of them do not fit the average aquarium lighting fixture.
The only thing anyone agrees on about reflectors is that the best ones are made of "specular aluminum," and are carefully shaped to direct all the light downwards...
Well, here's a little tip for you with languishing plants: Specular aluminum is made of the same element that kitchen aluminum foil is made of. What's more, aluminum foil has a hihgly reflective side, which is nearly as good as specular aluminum.
For an investment of just a few cents worth, you can tape regular aluminum foil onto the inside of your aquarium light fixture, and while it will not double the output of your lights, it DOES improve plant growth. You will probaly not be able to aim it much, but with aluminum covering most every part of the inside, you can be sure that a lot of the "wasted" light that normally gets absorbed in the material of the fixture will instead get projected at the general direction of the aquarium.
Of course, this may slightly increase the risk of electrical shock when using the device, and a 3 prong grounded plug is desirable. You;ll also want to be sure not to wrap the contacts of the bulb in foil, and unplug it whenver you intend to service the device.
