I have a variety of tanks in my house (not all mine), but I'll give you some info on some of the things I've got.
1. What type of plant?
ANUBIAS - these are definitely my favourite. So easy to look after, and they can be mounted on so many things, AND there are multiple varieties. Also can work with low lighting if your tank gets some sun!
. I have amazon swords in a couple, and I love them, but I personally think they work better in a larger tank (not sure what tank you are planting). Um, blue strictas are nice if you have a tall tank. My mum used to have banana lilies, and they were lovely, but they took up a lot of surface area, which might not work well with bettas. Others but the names have escaped me! :(
2. What type of lighting do you use? All of our tanks use LED lights with white and blue lights together, however, some are brighter than others.
3. Do you add extra plant nutrients into the water? With my smaller tanks, no. I don't even have fish in some of my tanks and the plants are still thriving! But with the bigger tanks my family have, using nutrients such as flourish help fill out the tanks.
Hope that helps!