If you usually have a good Internet connection, one possibility (that I use) is for you to keep most files in Dropbox (or equivalent service) and unsync folders that you don't need. I do this for large data sets that I use periodically, and arrange for my videos and photos to be batched in folders with the year in the file name. If I want to watch a video I made two years ago, I just resync a folder, and it is soon available.

A disadvantage of this approach is that unsynced folders are not in Time Machine backups.