No clothes and diaper free is the way.
Kids just want to be free, and potty training is so much easier this way.
My son was fully potty trained by 18 months (including at night), and my daughter, who just turned one, only has occasional accidents if there’s no potty in sight.
If you don’t force your kids to wear clothes at home, they’re much more willing to get dressed when necessary, like when going out and about.

