Basically, tin snips (which cut more than just tin) are designed to cut metal as if it was paper. (though really, like using scissors to cut cardboard.) You'll get straight and relatively clean cuts out of them too, but as it's tricky to clean up a poor cut, mark your area first with either a knife or pencil.
- Handle Length
- The longer the handles, the more torque you'll have, making it easier to cut thicker metal.
- Small pairs like mine, however, work just as well for most hobby applications and are easier to store.
- Handle Grip
- Something as simple as some rubber on the handles makes cutting with these much more pleasant when applying this much force.
- Blade Length
- This allows you to make longer clean cuts without bending the metal to get the large bulky snips across.
Also, by placing whatever you're cutting as far back as you can you can get more force. BE CAREFUL, since these could easily take a finger off - and for thinner material, you may have to hold the piece straight when cutting.
Otherwise, they work just like scissors do.