This will depend on how you are going to be tenderizing your meat. All mechanical methods work in the same way as you'll want to give the same attention to all parts of meat and do this on both sides of the cut, especially if it's a thick piece of meat. For the meat mallets, it's best to cover it in a material such as wax paper to prevent any mess. The amount of time you tenderize it is up to you, but it's better to pay more attention to meat's worst cuts. Whether you are using a mallet or a handheld stamp, it's important to be safe, and this usually means keeping your non-dominant hand well away from the tool.