to not use 30 for power in. None of them apply in a basic on/off relay, but it is not a necessity to use 30 for power in, in any case. The reasons not to use it are too long, complicated and boring, plus they don't matter for your application. Same goes for 85 and 86. It does not matter which way you hook them up. One needs power, the other needs ground. The relay doesn't care which is which.