Just a bit of advice that's worked for me for over 50 years of changing out tires and tubes on small to larger motorcycles.
When you have the first bead into the wheel and you insert the tube and get the stem through the wheel and the nut just started on the tip, put just a little air in the tube to inflate it round. This eliminates any flat flaps in the tube that always seem to get pinched when you put the second bead into the rim.
It's not idiot proof, but this idiot has pinched a LOT less tubes since using this little trick of inflating the tube "just a bit" before the second bead gets worked into the rim.
And yes, three hands helps a lot...
