The easiest live plants are: anubias and java fern. These plants don't actually get planted into the substrate, but tied on to stone, wood, etc. in the tank. They are readily available in just about any LFS and very easy to deal with. No ferts needed (other than the fish poo), no special lighting requirements - just 4-6 hours of light a day is sufficient. I'm far from a plant expert, still very much new to that, but I've had my live plants for over 2 years now, and they have grown and spread and grown and spread. Lots of little fern plants now. My anubias is quite large.