A great place to practice assertiveness is at home.

If an unsolicited person knocks on your door, to sell you a product or a religion, here’s your chance. It’s your sandbox. Assert your right to privacy.

Same if you get junk mail in your mailbox that prominently displays a sign “NO JUNK MAIL”. Call them. Ask to speak to the person who put illegal advertising in your mailbox. When they blame it on the deliverer, say “Do you realise you are legally responsible for any illegal action you pay someone else to perform?”

Awkward questions are a great way to be assertive. You never have to be rude - just persist with questions that have revealing answers.