I've been using 3M ATG transfer tape on strike plates for years. Similar stuff can be found in the flooring section of home improvement stores. Lay the striker plate on the sticky side, cut around it precisely with scissors, peel and stick. No glue squeezing out. Quick, perfectly neat and stays indefinitely through any weather. If you want it off, just roll it off with your thumb.
For leather grips, I give em a quick shot of spray adhesive, except for the last 1/2" where I'll be stitching.