Start with the maxi tags, the bigger the better. They look dumb on calves, but their ears grow. Use up the whole tag for your numbers, bigger numbers are easier to read. I find the liquid ink in bottles lasts longer than the pens. You just have to be carful when squeezing your bottles so as not to "blob" the ink. Try different bottles, some ink will burn into the tag different than others, as well different tags react to different inks. My favorite bottle of tag ink is no longer made, I am not sure what was in the ink, but it would burn so deep into the Allflex tags that you could almost read the number on the back side. I am not sure you would want to use a stencil as that would smear the ink under the stencil. I am not the neatest of printers, but I take my time when making my tags.