"Unconventional methods" refers to unique or unusual ways of doing something, different from the usual or traditional approaches. It involves using non-traditional techniques or strategies to achieve a goal or solve a problem. Full definition
Although I really love trying unconventional methods of parenting. (attachmentparenting.org)
But just as conventional power plants are now using unconventional methods for cooling, solar power plants have a wealth of options at their disposal. (gracelinks.org)
And perhaps it's because of the group's tendency to use harsh, unconventional methods for advocating in the past. (dietsinreview.com)