Give us a few more specifics about your set up.
Is your light a flourescent tube, or incandescent? - are you just using sand for substrate?
If you don't have any root tabs, or a soil layer, you are probably going to need to add something, or avoid plants that like rich substrates (I believe most stem plants are fine pulling directly from the water column, but things like amazon swords and sagittaria do better with their roots in a rich substrate).
You might want to look into some floaters to help pick up extra nutrients until your plants get established, otherwise algae might get a bit of a head start.
Glad to hear you are giving plants a try, I think they can add a lot, both aesthetically and in terms of water quality, to a tank. Just prepared for a few failures/disappointments, it's part of the learning curve.