My favorite foot/toe stretch is to put the fingers of your opposite hand between your toes (eg, right fingers between left toes), approaching from the sole of the foot. Really try to get webbing to webbing, so that there isn't any space,
That's what I like to do too, it really gives your toes a good experience of being spread out, but yes, I agree to do it carefully, ease fingers between the toes slowly, they might twinge, but they should relax after a minute or so.
Sometimes I'll sit there for 5 to 10 minutes like this before bed, as part of a chill out / foot massage routine. But then that's probably just me.
Another thing I like doing is pressing my metatarsals up and down with my thumbs, one at a time, in the hope of stretching foot muscles and getting some more lateral foot flexibility. A lot of foot muscles tend to atrophy in regular stiff-soled shoes. I remember when I first used to do this in the evening my 3rd and 4th metatarsals used to "crack" out of a tensed position when I pressed them up, but I think that's because of my Morton's toe and walking on the outside of my foot more...at least I assume that's what it is...!