Java Moss or Java Fern, guppy grass and Anubias are all easy beginner plants. The moss and grass can take over a tank fast if not trimmed regularly. The other two are very manageable with rhizome growth that can be easily clipped and removed if it becomes to large. Live plants also help to absorb nutrients from the water and aerate your substrate to prevent anaerobic conditions that can be deadly to fish. I used to use plastic or silk plants because I had Oscars and Cichlids but now I have remover them all and replaced with live because of the benefit of the oxygenation they provide and the nutrient reduction, so if I miss a water change it is not as big a deal as before when the nutrient, nitrates would build up rather quickly in the water. Anubias are free growers which means they pull nutrients directly from the water column and do not need to be rooting into substrate, it looks great on a piece of drift wood because it makes it look like a living tree under the water and because it has tough bitter leaves most fish won't even nip at it at all if you just leave it to free float. I hope this helps.