Wow, Ibanole, you are a great tipper. I tip 10-15% a dive and more if the service is better for some reason, ie: I required assistance for some reason, the boat team made the day more enjoyable through extra good humor, the DM made a effort to point out things under the water that we may have missed, etc. I tip more for the Atoll trips, not just because they cost more but because the crews work harder those days.
I generally dive every day, somedays in excess of 2 dives. I often don't dive with the same team of DM and Capt. though I am with the same outfit. So I keep track in my log book of who I dove with on which day and what I plan to tip them. At the end of my stay, I make out envelopes for each team, write their names and the amount on the outside of the envelope, seal them and give them directly to the teams if I see them or into the shop for distribution. I trust the shop I use to distribute the envelopes.