Should I upgrade to an SSD or add more RAM first?

Upgrade to an SSD first. Swapping your boot drive from an HDD to an SSD is the single biggest performance improvement for an old computer — boot times drop from minutes to seconds and apps open instantly. More RAM only helps if you’re actually running out, which you can check in Task Manager or Activity Monitor. An SSD speeds up everything that touches the disk, so get that first and add RAM later only if you see your system struggling.