I think the easiest way is to pick up a 90’s model on ebay (Hi8 or even an older DV) and shoot the footage with that.
However there are a few things you can do in post.
Use Levels to crush the blacks and whites so you’ll loose detail in the dark areas and blow out the lighter areas.
Saturate the colors for outdoor sunny shots, de-saturate them for low light shots.
Add grain.
Size down the footage, precomp and size up again without having the “preserve resolution” option checked to give a lower resolution feel.
If you don’t have a shaky camera, add camera shake.
Use Dust and Scratches to add white spots here and there simulating dropouts.
Play with the overall color balance when the camera moves between light sources (indoor and outdoor lighting- if it passes in front of a window for example) to simulate a slow auto white balance.
I suppose that there are many other things you can do, but this should give you a start.
Tudor “Ted” Jelescu
Senior VFX Artist