Just grab a double bevel file from bailey's and get after it... Keep the corner of the file dead center of the cutting point and it'll cut...
Remember, the angle of the underside of the top plate will dictate the speed at which you cut, but its a trade off for durability... If you're nicking the back of the tie strap, you'll have a good work chain...
As always, the more consistent you can keep your cutters, the better, but if the raker depth is consistent on all the cutters, it'll still cut good...
It's fun.. Enjoy your new addiction...