Klein Tools D228-8 Pliers, Diagonal Cutting Pliers with Short Jaw and Beveled Knives, High-Leverage Color-Coded Wire Cutters, 8-Inch 8-Inch Tool Set

Depends on your budget and patience and usual material really. I like snips because there's no mess. There's no metal dust, I can make coils and then cut them in my lap on the couch if I wanted to. Klein Diagonal Cutters should do you just fine for 18-14g mild steel or galvy, I've done 16g Stainless and 18g Titanium with them. Flush Cutters if you're on a budget and doing smaller stuff. The bigger snips won't be able to get in to small rings. When you're cutting your coils, do one ring at a time. If you're just starting and practicing hit the hardware store and buy some galvanized wire. You can get a spool of it for pretty cheap. It's not fine jewelry, you won't be wearing it on bare skin, and it'll make clothes/fingers stained black, but for the learning the mechanics of making/cutting coils, ring sizes and weaves it's easy, relatively strong, and cheap.