Good advice all round here - my experience (from Canada) is that in winter, the aircraft were in a heated hangar. On the odd occasion that they'd been out overnight, then an approved aircraft de-icing fluid (diluted IAW manufacturers instructions) was applied using a garden sprayer.
Do NOT, under ANY circumstances be tempted to de-ice using hot water or to scrape off as much hoar frost as you can with a credit card and say 'she'll be right'. You either defrost the lot properly, or you don't fly.