I planted two ten gallons, one with a retrofit kit that gave me 26 watts total
PC fluorescent, and another where I used the incandescent hood that came with the tank and put those pigtail fluorescent bulbs with an incandescent-type screw-in base. I use laterite mixed with gravel in one and plain gravel in the other, and I think you can get away with plain gravel if you use root tablet type ferts. I have planted in sand using the same root tabs. My crypts do very well in plain gravel, as does the hygro (mentioned above) and so far so good with swords. The smaller the gravel the better. If you have larger size gravel, just add some smaller and mix it in. Changing substrate over is very risky to your bioload (been there, made that mistake
) so be very careful and do it very slowly, if you need to remove some. Oh, also the bulb-type dwarf lillies (not aponogeton, tho that will work, too) with the arrowhead shaped leaves have done fine in small gravel. Once you start adding plants, increasing your lighting, adding ferts, you will want to think about
CO2, also mentioned above, and there are lots of ways to do that cheaply and simply.