It's my first set up too, but I've spent literally years doing my research while keeping freshwater!
First change I'd make personally is to get one of the outlets directed at the surface to create agitation, it will help keep the water oxygenated and the pH up.
If you click my build thread badge it'll take you to my build, everything is on there!
Below is a video of the set up. In terms of flow I've got a jebao rw-4 on virtually the lowest setting, but the flow pattern allows for different movement in the water which keeps food suspended and stops build ups on the sandbed.