not sure I'd call it easy, and it depends on the split rings. The plated ones I first grab with round nose pliers, grip tight and wiggle back and forth a bit in case the rings are stuck together. To actually open them up I use my thumb nail (non-dominant hand). Some of them are a royal pain, but those are usually the nicer looking ones. I haven't used sterling or gold filled ones, when I connect something with those I usually wrap or coil. Split rings for me are to connect clasps, eye glass leash ends, or sometimes earrings to make the ear hooks exchangeable (in case somebody wants a pair of earrings I'm wearing, to make it easy to put new hooks on. And in case somebody wants clip-ons. I have the findings, but I don't usually make earrings as clip-ons.)
Aloha, Maren HiloBeads: Beads - Beading Supplies - Hand-made Jewelry