Hi jtimms

I have only done a few so I may not be the best. I was told about 1/8 inch. I use 3mm or 3.2mm and it seems to work. I put a bit of bees wax on end of the screw. Screw in a bit then back off slightly, and repeat until finished. I am not sure if the backing off is needed but I was told to once so it has become a habit. I have also heard of people wicking a little superglue into the neck hole afterwards but I have not tried this.