Here are a few things I do to make sure I`m diving ...especially if I`ve never been diving with someone before. Do the check...BWRAF -- (Belts, weights, releases, air, final check) Ask them (if a total stranger you`ve been buddied up with what level they are how many dives/and what kind go over hand signals/location of where you will be (I like to dive on my buddy`s left side around their shoulder) The extra tank at the safety stop zone is always good. Some will put a strobe on the anchor line or some sort of identifier Some will put a weighted sausage on the bottom below where the boat is. Have fun and blow bubbles