You should be paid perhaps more custom than law but some employers are scummy.. I had an experience many years ago I did a free trial they asked me to come back I did the next day and then they decided they wanted another day.. after the 1st day I should left and never came back. Anyways after the 2nd day I never went back as she told me she wanted me to come back for more days maybe even 2 weeks before she knew i was right for the position. I asked to be compensated they refused blah blah they did finally pay me but they decided to try register me as an employee when I wasn't one at all. I never signed anything at all and I wasn't offered a job I was being used and they obviously did that to alot of people try to get free labour. They were very underhanded.

Be careful and my advice is to offer to work for 2 hours trial let's say as a waitress or bartender etc during a busy period so they can see how you perform.. they don't need a full day's work from you to see your skills or work ethic.. 2 hours is plenty and it minimises you wasting a whole day to potential scummy employers