If I know there is no pipes or wires behind in the wall I will then use a few nails, but if I can't be sure for whatever reason then I have used hot glue gun.
Got to batten when laying HEAVY tiles. My preference ,with lighter tiles,is to set the datum line at a height that will allow me to lay a course the full perimeter of the room(no battens). Can then tile down to the floor and then, as the datum row should have set ,can tile the top areas.
hit tysfoot,its all done to experience friend, one day you will stop using battons because you will have a better understanding of tile adheshive, you will be more confident but it takes time