[MyraVan]

The best cheap substrate is 1" of plain soil (garden soil, or potting soil from a garden shop) covered by 1" of small gravel (2-4mm size). Eco-complete, Onxy sand, Flourite, etc, all work fine, but they cost alot. Soil + gravel is extremely cheap and works very well. It's similar to what plants have in the wild!

You will almost assuredly need more light than comes with your tank. I'd aim for between 1.5 and 2 wpg, that is, between 15-20W of light. Note that this is W of flourescent light; incandescent light (plain light bulbs) put out too much heat and not enough light. Put reflectors behind the tubes to maximize light output.

Since you won't have over 2WPG, don't bother with CO2. Use some basic aquatic plants fertilizer from the fish shop if it looks like the plants need it once you get it set up.

This is almost the opposite ofr what Simpte is recommending. He is an advocate of the high-tech, high-cost , high-maintanance approach. The advantage of this is that you can grow pretty much anything. I prefer the low-tech, low-cost, low-maintenance approach. Your choice of plants is more limited, but you can still end up with a beautiful tank that looks very natural.

Oddly enough, many of the plants that Simpte recommended are ones that I'd recommend too. I have good luck with crypts, sagittaria, java fern, water sprite, dwarf 4-leaf clover (marsilea crenata), baby tears.