Plants need 4 things, although some may argue only 3. Nutrients, light, good substrate, and Co2. Some say you can go with plain sand, with good results, like Greggz, but from what i have seen, plants are bushier with a good substrate.
Nutrients: Read into Microdosing, you can order an EI dosing kit from Green Leaf Aquatics.
Light: Light and Co2 should be based off of each other, read into balancing the two. Any light designed for plants should be good, or you can buy some T5 grow lights from https://www.1000bulbs.com/category/t...ight-fixtures/
. A 2ft 2 bulb light should be good.
Co2: Definitely do your research. On a small tank like yours, DIY can be good: the King of DIY has a good video on that. If you have the money, look into a full pressurized Co2 system.
Substrate: Either sand with a bunch of root tabs or ADA aquasoil is good. Ecocomplete, stratum, and that stuff is pretty much inert. ADA soil can be bought on AquaforestAquarium website.