For cast and swaged lead bullets--The only way to know for sure what size lead bullets to use, is to slug your bore and mic the slug. That said, my handi (and most others that I have heard of) likes .459. Most people recommend .001 to .002 over nominal groove diameter. This fit combined with good lube and proper velocity will help eliminate leading.
If your gonna reload on your workbench, you need to make sure to keep your reloading components well isolated from your grease and oils as they do not mix well. If you get just a little oil on your finger and then handle your primers, you can ruin them in short order and never know it until you try to shoot them.
Don't skimp on the lube, lube every one, they're all gonna need cleaned anyway removing stuck cases can range from a minor annoyance to slightly more fun than getting a root canal with a chainsaw. If it feels bad going in, stop or its gonna feel worse coming out.