How should I prepare meat to be ground?
My husband and I regularly grind our own meat. What we do is trim the meat before cubing. If any connective tissue / silver-skin is on the outside of the meat or running through the meat we are getting it off of a larger piece of meat, which is much easier because you can get a better hold on it.

We also use a filet knife for trimming the tough tissue. It allows you to trim much closer and with much more control, minimizing any waste.

And last but not least, chilling the meat helps also. While you don't want it frozen, firm is easier to handle.