You're going to get a lot of conflicting advice, because there are a lot of right answers to this one.
For the past 2 months I've had a happy betta and happy plants in a 10 gallon ... I replaced the stock light bulbs with "Reveal" compact fluorescents, I forget the wattage but I think there's only one narrow enough to fit. I used these because the color temperature was close to 6500K.
I used plain aquarium gravel, about 2" deep, and used Flourish root tabs (PetSmart has them). I put in an Ocelot Sword plant, some crypts, and floated some moneywort. I think the floating stems were what made him happiest. Still he wasn't quite as active as he'd been in a slightly smaller tank with a ton of fake plants (he had more cover there, and was ironically "out" a lot more ... in the 10 he always hides behind the filter).
As I understand amazon swords are pretty easy too.
In contrast I also just started one with a fancy plant-specific substrate (ADA Aqua Soil), with sand on top, and I'll be using Flourish Excel to add carbon dioxide.
There's a lot to know about plants and lots of ways to do it -- I'm just starting myself -- but if you're up for just trying different things and seeing what works and learning as you go, go for it! The buy & sell area here has lots of people selling packages of plants inexpensively, and YouTube has tons of videos about how to plant each kind.