Velcro-fastened ice grippers sound like a good idea. The velcro closures are easy enough to put on and to take off. From my experience, however, these grippers are a little too easy to take off. In fact, they often fly off your feet just when you need them most. I have found them so annoying that I’ve taken them off when I’ve been out and have left them off. Friends of mine who’ve also had poor experiences using them have sworn off any removable grippers as a result and have reverted to the second method I’ve tried -- roofing screws permanently attached to the soles of my boots.
Screws attached to your boots is a more effective non-slip strategy. For one thing, they don’t come flying off as you’re walking. And the screw heads do give you a fairly good grip on the ice. The problem is you need an older pair of boots that both fit well and that you are willing to sacrifice to having screws attached permanently to the bottoms. In other words, once the screws are in, you can’t change your mind. And once you’ve decided that you can sacrifice the boots, you need to actually attach the screws or find someone else to do it for you.
An additional challenge is what do you do when you are in town and want to enter a store, a restaurant, or another public space? You can hardly walk onto someone’s floor, clicking little screws under your feet as you go. It would ruin the surface of the floor or tear up their carpet. But carrying around an extra pair of shoes and changing from boots to shoes and shoes to boots each time you enter or leave a building is impractical So the final result is: you will probably not wear those permanently altered boots either.
Now comes the third option, one which I’ve actually stuck with and used for the last two winters.