It's always worth having a good suit handy. You never know when you might need it, weddings, funerals, police interviews, magistrates court etc.
I'm sure there have been studies which prove magistrates court defendants in suits are dealt with less harshly than those in trackies and trainers. Mainly, because most magistrates are snobby twats who like to think they can look down on everyone from their elevated position on the bench.
The speaking thing is just practice.
Its amazing what appearance can do.
Also if what is said is delivered with confidence people listen.