As a fairly new diver myself with 30 drift dives in Cozumel (the OP's next destination), I second this advice to consider a private DM if the OP is diving in Coz without an established dive buddy. Being new to drift diving in Cozumel, and ascending to controlled safety stops and surfacing without ropes, there are HUGE benefits to such a strategy. All 30 of my Cozumel dives have been off of the smaller fast boats with 6 divers, rather than the big cattle boats which I find chaotic. Without exception in those 30 fast boat drift dives, we all dove as a group trailing behind/beside the single DM. The DMs never ensured the divers were buddied up -- leaving that up to the divers themselves. Though I always had my buddy, there were frequently solo divers present in the group. I would not myself want to do that solo-but-in-a-group strategy in Cozumel, because though the solo folks were close to us, they were also kinda doing their own thing and we buddies were focused on our own thing... not really close enough for an emergency. And no guarantee for the solos that someone was watching their back, which could be a concern in Cozumel's fast-moving currents. Consistently, the DMs would turn and periodically check everyone's air via hand signals, and we would begin ascent as soon as anyone in the group responded that they were at 700-1000 PSI remaining. For those not real experienced in drift diving at a location like Cozumel... again, there are no ropes. You must control your ascent and achieve the safety stop all on your own, while floating in the current in a cluster with your dive group. This ascent plan happened as described for all 30 dives across 3 different fast boat dive ops and many different diver groupings, with no exceptions. The Cozumel DMs never shared air, never sent a lone diver or buddy couple to the surface alone. On some of the trips, because we had a brand spanking newly certified companion join us, we used a private DM at both Scuba Mau and at Blue XTSea, with superb experiences at both. The private DM allowed us to keep our newbie's dive profile safe and at a good pace for him, without hijacking the experience for other advanced divers on the boat. The Private DM was an extra ~$50 a day (2-tank dives). It was worth it for us.