What upgrade should I make first?

Device Name DESKTOP-JJFSKQU

Processor Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz 3.59 GHz

Installed RAM 16.0 GB

Storage 477 GB SSD 512GB SSD

Graphics Card AMD Radeon RX 580 2048SP (16 GB)

System Type 64-bit operating system, x64-based processor