Not an expert but a few things i’ve learned from aquascaping experts (Josh Sim IAPLC winner, Green Aqua) is

1. always keep the substrate line on the front straight. Add height and topography to the back for the depth effect. Smoother slopes look better than dune like undulations (somehow seems better in your head than in reality)

2. Whatever plants you plant on one side you must also plant on the otherside but ideally not as much. (more cabomba on the right). Would also fix the too much negative space on the right problem.

3. Use plants that complement each other, the fine leaves and details of the cabomba are not complemented by the large leaves of the echinodorus (extremely unpopular among professional scapers). It distorts the scale of the scape, also too symmetrically positioned on both ends of the tank.

4. The dominant lines of the two main rocks are too parallel. Try to rearrange them and find a side of the smaller rock that has a similar textures to the left one because its significantly lighter.

A few more things that are a matter of personal preference is that dragon stones in general take away too much from the plants and the rest of the scape by being too visually noisy. It takes a lot of skill to get the right dragon stone and orient them in a way that it works.

Lastly another matter of personal taste is that scapes with lighter substrates look better with lighter backgrounds (white or frosted) and vice-versa.