I use both toe-warmers and hand-warmers at the same time to keep my hands warm. I will tape a hand-warmer to the inside of each wrist just above my palm, as that helps to warm the blood before it goes into your hands. Some days, that is enough to keep my hands warm by-itself, even without gloves. But on the really cold days, I will also stick a toe-warmer to the backside of each hand, and then put my gloves on. If I have to take my gloves on and off to handle fish, etc, I will sometimes tape them on with hockey tape to keep them from falling off. Make sure not to tape them too tight or you will cut off the circulation, which defeats the purpose.
I will also put them in my boots, on top of my socks by my toes, which does a great job of keeping your toes toasty on even the coldest days. So that would be two pairs of toe warmers and 1 pair of hand warmers for the day, which costs about $3-4 bucks, which is nothing compared to all of the other fishing-related expenses. Totally worth it to be able to keep my hands and feet from going numb.