Thanks Dan, you can even see in my set the amount of clearance(too much) with the jaws closed. It ends up putting "tabs" on the terminals. They should be tighter. Mine came with instructions as well. Sucks as they feel like a quality ratchet set but the open barrel crimps are terrible.
Those W style crimps are pretty tricky. You have to line everything up perfect and you will need to practice on a handful of connectors first.
Here they are. And like Mike says, practice! It's a learned skill.
Open Barrel Crimper Tool for Molex Style DELPHI AMP TYCO Terminals 24-14 AWG | eBay