Follow this template and you should be golden. It's the basic "natural planted tank/Walstad method" type of bowl. There are also a few journals on here that will give you great inspiration and guidelines to follow.
Rule of thumb is, you want to put as much greenery in there as possible and things that grow as fast as possible, so pack it full of stems, some dwarf sag and maybe some moss afterwards. But at the beginning, the faster it grows, the better it is. And variety because not everything will grow well so you need to be able to adjust. And you'll be much better off with some organic potting soil under your sand because it'll provide nutrients for the plants without polluting the water column (if it's capped right, unlike my attempt at doing so).
Rule of thumb is, you want to put as much greenery in there as possible and things that grow as fast as possible, so pack it full of stems, some dwarf sag and maybe some moss afterwards. But at the beginning, the faster it grows, the better it is. And variety because not everything will grow well so you need to be able to adjust. And you'll be much better off with some organic potting soil under your sand because it'll provide nutrients for the plants without polluting the water column (if it's capped right, unlike my attempt at doing so).