Hi and welcome to UKaps 🙂
That is a very hard question to answer as we do not know what you like and as it is your tank, you need to have a tank that suits your taste, your time available, do you want a planted tank, and so on.
Personally for me, I would get rid of the neon blue gravel for a start.
How about if you check out the Journals or the photo sections on here to get some ideas?