correct way to pay

Hi, I have noticed that when I pay for things I get the impression that I should not hand the money directly to the person but put the money down usually in a tray for them to pick up any change is given to me and placed in my hand is this correct?

Yes, pretty much so, but it's not always that strict.

Often the change will be placed in a tray too- there is not really a set rule for this. If there is a tray right in front of you then you might want to use it. For expensive items in high end stores there will always be trays for both payment and change.

At convenience stores and fast food outlets for example it doesn't really matter whether you hand the money straight to the cashier or put it on the counter or what you do.